INTRODUCTION ...... 2 WHAT IS A FISH? ...... 2 FISH SHAPES ...... 2 ORIGINS AND DIVERSITY OF FISHES ...... 3 CLASSIFICATION OF FISHES ...... 4 1. BONY FISH ...... 4 INTERNAL STRUCTURE OF A BONY FISH ...... 5 SCALES AND SLIME ...... 6 SWIMMING WITH FINS AND TAILS ...... 6 THE SENSE ORGANS ...... 7 FEEDING ...... 8 HOW FISH BREATHE ...... 9 BUOYANCY IN WATER ...... 9 LIVING IN FRESH OR SALT WATER ...... 9 REPRODUCTION ...... 10 SEX CHANGES IN FISH ...... 10 2. CARTILAGINOUS FISHES ...... 11 EXTERNAL STRUCTURE OF A CARTILAGINOUS FISH...... 12 CARTILAGINOUS FISH SKIN TYPES ...... 12 TAIL SHAPES ...... 12 INTERNAL STRUCTURE OF A CARTILAGINOUS FISH ...... 13 FEEDING ...... 13 FEEDING ...... 14 REPRODUCTION OF BEARERS ...... 14 3. JAWLESS FISH ...... 16 EXAMPLES OF FISHES FOUND IN THE OCEANS AROUND SOUTH AFRICA ...... 17 1. COELACANTH ...... 17 2. SHARKS, RAYS, SKATES AND CHIMAERAS ...... 17 3. REEF FISH ...... 19 4. PELAGIC FISH ...... 22 5. EELS ...... 22 5.1 MORAYS ...... 23 6. SEAHORSES ...... 23 7. SUNFISH ...... 23 CONSERVATION THROUGH RESEARCH AND OBSERVATION ...... 24 CONSERVATION VERSUS ECONOMIC FISHING INDUSTRIES ...... 26 1. OVERVIEW ...... 26 2. STATUS OF CERTAIN FISH STOCKS IN 2001 ...... 28

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 1 INTRODUCTION WHAT IS A FISH? A fish is a cold-blooded vertebrate that lives in water, breathes by means of gills and has fins for stability and movement. Most, but not all fishes, have scales and a lateral line. FISH SHAPES Fishes can have many forms (see the illustration below). They can range in size from less than 1 cm (a goby) to over 12 m (a whale shark).

A. Lamprey B. Hagfish C. Shark D. Ray E. Chimaera F. Lungfish G. Teleost

They do not include seals, whales and dolphins (mammals), turtles and sea snakes (reptiles) or shrimps, lobsters, and crabs (crustaceans) or mussels (molluscs)

Some marine and freshwater invertebrates (animals with no backbone) and some animals with shells (such as molluscs) are called ‘shellfish’. Therefore true fish may be called ‘finfishes’.

ICHTHYOLOGY is the study of the classification and the biology of fishes.

FISHERIES SCIENCE is the study of the management and utilisation of fish populations.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 2 ORIGINS AND DIVERSITY OF FISHES The fish came first! Ancient fishes first appeared in the fossil records over 500 million years ago, more than 100 million years before any other vertebrate group. Fishes are therefore the most ancient, and all other vertebrate groups (amphibians, reptiles, birds and mammals) evolved from them. Fish first laid down the basic ground plan and functions of vertebrates. These include the 10 organ systems: skeleton, muscles, gills (respiratory), digestive, blood circulation, kidneys (urinary), reproductive organs, hormone (endocrine) systems and the nervous system (including the sensory organs), as well as the basic locomotion systems. But fishes are not primitive because they are ancient. Some of them are very advanced and have well developed senses of sight, taste, electro reception, vibration reception, in addition to internal fertilisation, parental care, placental nourishment of the young, live birth, learning and memory. Many of the ‘inventions’ of man were first evolved by fishes, for example – echolocation, sonar, camouflage, electro reception, electrical discharge and so on. Fish species constitute almost 50% of all living vertebrate species and the extinct fish species outnumber all other vertebrates.

Pie chart of living vertebrate species.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 3 CLASSIFICATION OF FISHES Fishes like other animals may be classified based on the ancestral relationships and on their feeding and breeding behaviour. This is known as Taxonomic classification.

The evolutionary sequence of fish is thought to begin with the jawless fish, then the cartilaginous fish followed by the bony fish. The elephant fish shows characteristics of both cartilaginous and bony fish. However, for practical purposes, as there are a greater variety of bony fish than cartilaginous fish in the Two Oceans Aquarium, the bony fish are here dealt with first.

The main groups of fishes that are described in the following pages are: 1. Bony fishes (Class: Osteichthyes) with a skeleton of bone such as lungfishes, coelacanth, and all ray-finned fishes. Their bodies are usually covered with thin scales. They have a single gill opening. 2. Cartilaginous fishes (Class: Chondrichthyes) with a skeleton of gristle or cartilage such as sharks, chimaera, skates and rays. Their scales are buried in their skin. There are several gill openings. 3. Jawless fishes (Super Class: Agnatha) such as hagfish, and lampreys that have no jaws or scales. The skeleton is made of cartilage. There are several gill openings. 1. BONY FISH As fishes live in water, a medium 800 times denser than air, and as water is buoyant they do not have to support themselves, but density causes friction against their bodies so they have to be streamlined. EXTERNAL STRUCTURE OF A BONY FISH

Operculum (gill cover) Scales Water taken through Dorsal fin These are Eye the mouth is forced This single fin extremely thin, out over the gills Sight is well developed in most acts as the overlapping bony beneath this cover. fish and the eyes are most main ‘keel’ plates that protect In the process, Lateral line sensitive to yellow-green the preventing and streamline the oxygen is absorbed The lines of dots wavelengths that penetrate the fish body. They contain and waste products along the flanks are furthest into water. rolling during pigment cells, released. tiny holes leading to swimming. although apparent a canal that runs colour in many the whole length of fishes is produced the fish. Nerve Nostril by reflected light. endings respond to changes of water Many fish have a highly pressure enabling developed sense of smell. the fish to detect The nostrils do not connect vibrations in the to the mouth. water.

Mouth Caudal fin (tail) The shape and position varies Most fish swim by between surface, midwater & sweeping the back bottom feeders. part of the body from side to side. The tail Anal fin fin helps to convert Pectoral fins that movement into (paired) This single fin acts as Pelvic fins Cloaca a stabilizer during forward thrust. Fish use these to (paired) (vent or anus) swimming & in males steer and change These also This is the of certain species is direction in the help a fish opening for modified for breeding water – even to to control urinary, digestive purposes. swim backwards! its position. & reproductive systems.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 4 INTERNAL STRUCTURE OF A BONY FISH The internal organs of a typical bony fish are packed into the cavity in the lower front half of the fish. The rest of the body consists of muscles used for swimming.

1. eye 9. anal rays 17. spleen 2. skull 10. anal spine 18. pyloric caeca 3. brain 11. cloaca (vent or anus) 19. liver 4. vertebral 12. kidney 20. heart column 13. swim bladder 21. gills 5. dorsal spines 14. ovary or testes 22. gill rakers 6. dorsal rays 15. intestine 23. tongue 7. lateral line 16. stomach 8. muscles

THE BODY SHAPES OF BONY FISH are adapted to their environment and this illustration shows the terms used to describe their physical appearance.

1. Square in cross-section e.g. boxfish and cowfishes. 2. Robust e.g. sea breams, rockcods. 3. Elongate, e.g. snoek and eels. 4. Compressed (that is flattened from side to side e.g. butterfly fish, moonfish, batfish. 5. Flat or depressed e.g. soles and flounder.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 5 SCALES AND SLIME The majority of bony fishes are covered with thin transparent plates called scales. Scales are in fact outgrowths of the skin and provide the animal with a flexible covering that, together with mucus (slime) secreted by the glands in the skin.  forms a barrier to bacteria and fungal infection  preventing the loss of body fluids (seals the body from osmoregulation). Scales grow with the fish and the ‘annual rings’ are useful to determine a fish’s age and history.

1. Cycloid (smooth edged) 2. Ctenoid (rough edged) 3. Lanceolate (sharp and deeply embedded in the skin e.g. marlins) 4. Rhomboid (not overlapping, criss-cross pattern e.g. triggerfish.

Collection of fish for aquarium display: Need to collect animals of the best physical quality to display in exhibits.

Hake cannot be displayed because it is difficult to catch them from the harbour wall. If anything disturbs the slime covering the skin of the fish – the flesh disintergrates. Similar problem in collecting snoek.

Sardines shed their scales to escape from predators. Scales are shiny and confuses predators.

Precautions taken during collection to prevent damage to scales and slime:  Fish caught on hook and line rather than using nets as it damages the surface of the fish. Hooks used are barbless.  Stretcher is then placed into water to scoop the animals out or plastic bags. The stretcher is kept as smooth as possible to reduce abrasion – seams are on the outside.  Plastic bags and wet sponges are kept at hand in the event it is needed  The collection tank are made using fibre glass. These are made smooth using sandpaper(?).  The inside of all the collection tanks and those in quarantine have black lines painted on them so that the fish can sense their boundaries and not bump into the sides.

SWIMMING WITH FINS AND TAILS (a) FINS

Fishes can move in 3-D, forwards and backwards, left and right as well as up and down. They wiggle through the water with a series of S-shaped waves. Their dorsal and anal fins act like keels keeping them upright while the paired fins are used like oars to slow down or turn corners. A fin has a thin layer of skin supported by fin rays, which may have stiff and bony spines or soft and flexible (rays).

 If the pelvic fins are set far back they are probably fast swimming species.

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 Slower moving fishes that live on reefs for example have large side fins, as they need to be able to manoeuvre around obstacles.

 If the pelvic fins are placed well forward, sometimes even further forward than the pectorals, it is then typical of a bottom dwelling hovering species.

(b) TAILS

The tail or caudal fin is, in many fishes, the main means of forward 1. Pointed. propulsion and it uses the powerful muscles in the caudal peduncle with a 2. Rounded. sweeping side-to-side motion. 3. Truncate. Taking the shape of the tail and the general body shape is usually an indication of the fish’s speed through the water. Faster, wide-ranging fish 4. Emarginate. such as mackerel and tuna have forked tails, which are hydrodynamically 5. Lunate. more efficient than the rounded tails of the slow-moving fish such as kob 6. Forked. and rockcods.

THE SENSE ORGANS Like us, fish can smell, see, taste and hear. They also have special sense to help them find their way or search for food.

1. Seeing. A fish’s eyes bulge out at the side of the head and it can see clearly to the front and detect movement at the sides. Many fishes can see colour. They focus their eyes by moving the lens not by changing the thickness of the lens as we do. Fishes have no eyelids as the water constantly bathes their eyes. 2. Smelling. A fish has a good sense of smell. Most fishes have a pair of nostrils that they use for smelling not breathing. 3. Hearing. Fishes have ears inside their heads, which pick up sound vibrations from the water. Some fish use their swim bladder, like a drum, to magnify noises while others, the grunters, make loud drumming noises which bounce back from rocks enabling them to find their way in murky conditions. There are small bones in the ear called otoliths. The otoliths rest on sensory pads and are used for balance, telling the fish whether it is upside down or on its side.

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4. Lateral Line. Most fish have a lateral line running along each side of their body. Little holes in the line can sense vibrations in the water, which may be made by other animals or waves bouncing off obstacles or maybe sound waves. The lateral line is particularly helpful when fish swim in large shoals or a predator approaches. 5. Tasting and feeling. Some fishes have feelers or barbels on their chins, mouths or even fins. The fish uses these to taste and search food. 6. Making and sensing electricity. A few fish (such as the electric eel), can make electricity. They can sense anything that alters the electrical field they produce. Coelacanths use electrical impulses to find food in the darkness. FEEDING Fishes do not have regular meals. Some, like pilchards and sardines, constantly sieve plankton from the water as it passes through their gills, while certain predators may go without food for days or even weeks. The shape and position of the fish’s mouth gives clues as to how it catches its food. Snoek have ferocious sets of teeth and are predators on fish and squid. The mussel cracker has powerful jaws and large grinding teeth used for crushing shellfish and sea urchins. The sea horse sucks in small food items, while the teeth of a parrotfish are fused into a sturdy beak for nibbling hard corals. The bones in a fish’s head are not usually fused together so the fish can move and expand its head and jaws when feeding. Some fish blow small prey out of the sand.

In the illustration above the shape and position of a fish’s mouth can give clues to its feeding behaviour or hunting strategy, for example:

1. The elongate jaws of fast-swimming surface carnivores e.g. Needlefish. 2. The protractile jaw (shown as retracted 2a and extended 2b). e.g. rockcods 3. The superior or undershot jaw typical of slow-swimming predators such as rockcods that ‘ambush’ their prey, but also of many other fishes including the fast-swimming pelagic wolf herring. 4. The inferior or underslung jaw also typical of many fishes from anchovies to bottom- dwelling barbels. 5. The terminal jaw where the mouth is at the tip of the snout typical of fishes, which nibble or probe on the reef e.g. butterfly fish and wrasses.

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Fishes feed on a wide variety of foods, but the following major feeding groups are recognised.

Herbivores Feeding mainly on plants - either phytoplankton, algae or higher plants. Scavengers Feeding on the remains of plants and animals, and associated organisms, usually on the bottom. Detritivores Feeding on detritus and associated diatoms and bacteria. Predators Feeding on other animals, including zooplankton, other fishes, and shellfishes. Worms etc. Omnivores Feeding on plant and animal food.

HOW FISH BREATHE All animals from fleas to flamingos to fishes need oxygen in order to survive. On land oxygen is contained in the air breathed into the lungs. Water dwelling creatures generally use gills to extract oxygen that is dissolved in the water. Water enters the mouth of a fish and flows out between the gills, which are richly supplied with blood. Oxygen passes through the thin gill membranes and into the fish’s blood and is then carried around the body. Gill arches Beneath the gill cover is a v-shaped bony arch. There are two rows of gill filaments with many leaf-like folds to give a large surface area for absorbing oxygen. The surface area of the gills is 10 times the area of the fish’s body. Stiff gill rakers on the arch sieve food and debris from the water before it passes between the gills. BUOYANCY IN WATER Swim bladders The hydrostatic function of the swim/air bladder enables a fish to maintain the same weight as the surrounding water it lives in, enabling it to float in the water without the tendency to either rise or sink, exerting the minimal muscular effort.  As a fish rises the pressure in the surrounding water decreases and the gas in the bladder expands. To counteract this and to restore equilibrium at the new level, gas is absorbed or allowed to escape (depending on species).  Conversely, if the fish swims downwards, the hydrostatic pressure increases; the body becomes heavier and tends to sink. By increasing the gas in the swim/air bladder the fish is able to equalise.  Rapid exchange in external pressure of fish causes the gas in the air bladder to expand, the body tends to shoot upwards, and the swim/air bladder is forced out through the mouth. (See Barotrauma, page 4, AQUARIUM OPERATIONS).

Ragged tooth sharks do not have a swim bladder. Instead they take a gulp of air at surface to help with buoyancy.

Precautions taken when collecting fish at depth:  Bring fish up slowly to the surface to reduce barotrauma.  If fish is experiencing barotraumas e.g. swimming lobsided obe it is brought to the surface, determine where the swim bladder is positioned in the body of the fish – this is not the same for each fish species  Insert a hyperdermic needle into surface of skin and swim bladder to remove the excess air.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 9 LIVING IN FRESH OR SALT WATER The saltiness of water has a great effect on a fish’s internal chemistry.  Marine fishes tend to lose water to the salty sea surrounding them. They have to drink lots of water and produce a little highly concentrated urine.  Fresh water fishes on the other hand absorb water and must make large quantities of dilute urine to remove the excess water. A relatively small number of fish species (e.g. salmon, eels, grunter and moonies) are adapted to live in both sea and fresh water.

Application for treating fish: If fresh water fish are a bit stressed – aquarists may add a little more salt to the water.

REPRODUCTION Almost all bony fishes lay eggs but there are two main categories for reproduction:  High numbers, small sizes of eggs. Used by fishes living in unpredictable environments to spread the risk widely in order to increase their chances of having some of their young survive.  Small numbers, large sizes of eggs. Used by fishes living in predictable environments where there is strong competition from a large number of species and they invest a lot of time and energy in a few, large young.

There are three main breeding groups of fishes Non-guarders Produce large number of small eggs released into the water column or on the bottom where they are fertilised. The parents abandon the eggs and do not guard them. Example : Herrings, catfish, kingfishes and most familiar fish. Guarders Make a nest or burrow in which eggs, embryos, and/or juveniles are guarded until they are able to fend for themselves. They produce an intermediate number of young. Example : Bass, some tilapias, salmon, clown fish, steenjie. Bearers* Produce a few, very large eggs (coelacanth’s are the size of an orange) which hatch either within the body, in the mouth or in skin pouches (seahorse and pipe fish). These are only released into water once they are well developed. Example : sharks, rays, coelacanths, surfperches, some catfish *Reproduction of cartilaginous fish - see next page

SEX CHANGES IN FISH Sex change is common in many families of fishes including the rockcods, seabreams, wrasses, parrotfishes, anemonefishes and damselfishes. Some species are able to change from female to male and are known scientifically as protogynous hermaphrodites. Others change from male to female and are known as protandrous hermaphrodites.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 10 Generally, sex change is regulated by population structure. On coral reefs, where space is limiting and competition for prime spawning sites is fierce, species generally change sex from female to male.

Why? In simple terms, it makes good sense to be a female when small and unable to defend a spawning site. Small females can spawn with large dominant males for several years. When older, the female may become sufficiently large to defend a site and, if the dominant male is removed (usually by predation) she may change sex and become a male. Now ‘she’ can spawn with many females and produce large numbers of offspring.

The simplest example of a fish changing from male to female is the anemone fish (clown fish). The life of this species is linked to a single anemone. Its ‘world’ is rather small and, in this case, it makes good sense to start off as a male and change to a female. Why? Generally, there is only space for one breeding pair on an anemone. Males produce sufficient sperm to fertilize literally hundreds of females so, in this instance, there is no advantage in being a large male. There is however, a distinct advantage in being a large female – the larger the female the more eggs she can produce! So the smaller fish of the pair is a male and the larger fish is a female. Should the female be removed (by predation or disease), the male will become a female and an immature fish, which has been waiting on the outskirts for this opportunity to arise, will come in and become the male. The examples given above are the most simple known to man. Sex change is more often a lot more complicated than this, but it works for many species.

Which fishes in the Aquarium change sex? Sea goldies (rockcods) Red stumpnose Yellowbelly rockcods Clownfish Red Roman (seabream) Blacktail (seabream)

2. CARTILAGINOUS FISHES Evolved about 450 million years from their bony fish ancestors. There are about 960 species in cool and warm oceans worldwide of which about 300 species occur in southern Africa. The two main groups are: Sub Class: Elasmobranchii - Sharks, skates and rays with the upper jaw not fused to the skull, teeth usually separate and 5-7 pairs of gill openings. Sub Class: Holocephali – Chimaeras with the upper jaw fused to the skull, teeth in the form of solid plates, and only one pair of external gill openings with a soft gill cover.

Important characteristics of cartilaginous fish:  Gristle-like cartilage skeletons.  A number of gill slits rather than a single gill opening.  All males have claspers.  Internal fertilisation.  43% of cartilaginous fish (sharks and rays) lay eggs.  Egg incubation periods vary from 1 to 15 months.  Have true jaws and teeth and many species have rows of teeth, which move forward as others break or wear out.  Are primarily marine fish with some freshwater species.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 11  Most have a highly developed sense of smell and are acutely sensitive to vibrations, which they sense through their lateral line, allowing them to hunt their prey in very murky waters where sight is not effective.  Maintain a high concentration of urea in their blood and other tissues so as to maintain the ionic balance of their tissue relative to seawater.

EXTERNAL STRUCTURE OF A CARTILAGINOUS FISH

External structure of a guitarfish 1. Eye 2. Spiracle 3. Tubercles 4. First dorsal fin 5. Second dorsal fin 6. Caudal fin 7. Pelvic fin 8. Pectoral fin CARTILAGINOUS FISH SKIN TYPES

Cartilaginous fishes have placoid scales which are not exactly like the ‘typical’ scales of bony fishes. The overlapping pattern looks similar to scales but the difference is that these are tooth-like and each has a central core overlaid with dentine and coated with enamel

Their skin is very rough and abrasive and sharkskin (known as shagreen) has wide applications and is still used in primitive societies as ’sandpaper’ and to make non- slip handles on knives, spears and other tools.

The four skin types here are from: 1. Tiger shark, 2. Dusky shark, 3. Sandbar shark 4. Lesser guitar fish TAIL SHAPES .

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 12 Forward movement in sharks is the function of the tail. The shape of the tail can, in most cases, give an indication of the speed of the fish.

1. The mackerel shark is the swiftest and its tail is a great sickle shape. 2. and 3. The grey and thresher sharks have robust tails giving them great speeds. 4. and 5. Caudal fins of the spiny dogfish and cigar sharks and are not as powerful. 6. Ragged tooth and hound sharks have a reduced lower lobe showing they are slower moving. 7. and 8 here the lower lobe is almost lacking in bottom-dwelling, and slow moving catsharks and shysharks.

INTERNAL STRUCTURE OF A CARTILAGINOUS FISH

Internal structure of a shark 1. nostril 10. dorsal spine 19. spiral valve 2. eye 11. second dorsal fin 20. pancreas 3. brain 12. caudal fin 21. stomach 4. spiracle 13. muscles 22. pectoral fin 5. nerve cord 14. claspers 23. liver 6. vertebrae 15. cloaca 24. heart 7. muscles 16. pelvic fin 25. gills 8. testis 17. spleen 26. pharynx 9. first dorsal fin 18. intestine 27. mouth

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 13 FEEDING Cartilaginous Teeth Although variations occur, the teeth of most cartilaginous fishes usually fall into four categories and it is possible to understand their eating habits. 1. The great white and grey sharks have triangular heavily serrated teeth suited to cutting and tearing. 2. The tiger shark has slanted cocks-comb teeth suited to cutting and tearing. 3. The ragged tooth shark has triple-cusped pointed teeth suited to grasping and piercing. 4. Ray and guitarfish have round teeth that provide a mill-like grinding action for crushing mollusc and crustaceans.

How the jaws work The jaw of many fast swimming sharks can hardly be seen as it fits so neatly under the top one allowing for a smooth profile. However, when the mouth is open - the upper jaw seems to dislocate therefore opening up the mouth to its fullest extent.

REPRODUCTION OF BEARERS Typical Life Cycles

There are three main methods of reproduction amongst the bearers

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 14 Oviparous: The eggs develop and hatch outside the body of the female. The embryo, with an adequate yolk supply, is encased in a leathery egg case called a ‘mermaid’s purse’ laid by the female and attached to suitable material (e.g. seaweed) by coiled tendrils. A fully formed young shark hatches from this case. Catsharks and shy sharks reproduce in this way and the egg case shown here is just one example of various shapes laid by different sharks, skates and rays. ______

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 15 Ovoviviparous: Most common mode of reproduction where the embryo hatches from an egg while still in the uterus. The young is fed by a yolk sac before being born in an advanced state. Some sharks and dogfish reproduce in this way. ______

Viviparous: The embryo hatches from an egg and is fed either by a placental connection or through a form of uterine milk that bathes the embryo within the uterus. Gestation period can vary from 2 months to 2 years before free-swimming young are born. Examples of this are the Great white and Hammerhead sharks.

3. JAWLESS FISH Although many ancient and now extinct fish were ‘jawless’ the only surviving ones today are the hagfishes and lampreys. They are found in cool, temperate oceans in the Northern and Southern hemispheres. There are about 83 species worldwide and 4 species in southern Africa.

They have:

 Cartilaginous skeletons and eel-like bodies with no scales.  Paired rudimentary eyes and no true teeth or vertebrae.  The gills are carried on the one edge of the gill arches and are fused to the skull.  They have fins and a simple suction mouth.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 16 EXAMPLES OF FISHES FOUND IN THE OCEANS AROUND SOUTH AFRICA 1. COELACANTH The coelacanth is the only surviving member of the ancient super-order of lobe-finned fishes, the Crossopterygii. It first appeared in the fossil record in the Devonian Period 375 million years ago. The earliest coelacanths lived in shallow fresh waters, but during the Mesozoic era these and many other fish invaded the sea. Although fossils have been found on every continent except Antarctica, none date from the time after the Cretaceous Period, 65 million years ago. For this reason the coelacanth was long presumed extinct, until it was rediscovered in South Africa in December 1938. Studies in the Comores have shown that coelacanths spend daylight hours in groups of up to 14 in caves in the steep barren lava slopes of volcanic islands. The caves lie at approximately 200 m and the coelacanths can descend to 250-300 m to feed on benthic fish. Females are larger than males and are ovoviviparous. The eggs, the size of an orange, are retained in the female’s uterus, where they hatch and the female gives birth to multiple live young. The largest specimens have been 1.8m long and weigh 85 kg.

2. SHARKS, RAYS, SKATES AND CHIMAERAS There are some obvious external differences that distinguish rays and sharks. Of these, the position of the gill openings and the arrangement of the pectoral fins are most characteristic. Rays have their gill openings located on the underside of the head as opposed to the lateral gill slits of sharks, and their pectoral fins are enlarged into the typical flattened disc. 2.1 RAGGED TOOTH SHARKS (Also known as the grey nurse shark & sandtiger sharks).

This shark is robust, extremely plump-bodied and has a pointed snout. The overall colour ranges from light brown to grey with a pale underside. Large brown spots cover the body but these may fade with age. Can attain 3m in length. Both jaws carry a few rows of long pointed teeth that it uses to pierce and grasp the fish rather than ripping off a chunk like the Great White. A ragged tooth shark will have approximately 20,000 teeth in its lifetime. Their reproduction is different to other ovoviparous sharks in that the ovary and oviducal gland produce different types of egg capsules during the 9-12 months gestation period. After their own egg yolk supply is used up, the embryos begin feeding on other eggs in the uterus. At about 10 cm the embryos begin to feed on their smaller unborn siblings as well as eggs during the last 2 or 3 months of the gestation period the single remaining embryo in each uterus feeds on enlarged egg yolk capsule. – Intra – uterine canabalism.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 17 2.2 SMOOTH HOUND SHARK A common shark especially abundant along the shallow sandy beaches of False Bay and areas of the southern Cape although they can be found at great depths too. They prefer to swim sluggishly along the bottom and their diet is mainly composed of lobster, hermit crabs, and squid. The female can have up to 25 young which are born alive after a gestation period of nearly a year. Many specimens have distinct dark spots on the upper part of their bodies.

2.3 SPOTTED GULLY SHARK The overall colour is dark grey with lighter underbelly and black ‘inkspots’ on its skin. Numerous rows of teeth are set in a large wide jaw and arranged in pavement fashion. In summer this species congregates in shoals in False Bay for breeding and the females are ovoviparous. Endemic to South Africa.

2.4 STINGRAYS There are about 89 species in this family, which occur, in marine, brackish and even freshwater. Stingrays are bottom dwellers and often lie partially buried under sand or soft mud. This, coupled with their brown or mottled body covering, makes them totally inconspicuous even in clear water.

2.5 EAGLERAY This is a brown ray with large eyes and spiracles on the sides of its head. The females give birth to 3-7 young after a year’s gestation period. Although not poisonous to man, the poisonous spines on the tail can give a painful wound which must be soaked in very hot water to destroy the toxins.

2.6 GUITARFISHES OR SANDSHARKS The forward part of the body, including the head, pointed snout and large pectoral fins, is flattened and shovel- or wedge-shaped. A row of small, closely set, dermal denticles forms a ridge along the midline of the back. The mouth and gill slits open ventrally. The eyes and spiracles on the top of its head are an indication of this family's bottom-dwelling habits. They prey mostly on shellfish and during summer, females give birth to a number of live young.

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2.7 CATSHARKS AND SHYSHARKS. Mottled or striped markings provide camouflage to these sluggish, bottom- living sharks that are found in both coastal and deep, oceanic waters. They are nocturnal and feed on small fish, octopus and other invertebrates.

2.8 JOSEF’S OR ELEPHANT FISH These unusual fishes belong to the Chimaeriform fishes once diverse and numerous but now mostly extinct. It is not known if they share a common ancestor with the shark, however, like the shark they have a cartilaginous skeleton, and no rib cage. They have a single gill slit like bony fishes. The female deposits only 1-2 brown egg capsules on the seabed after being internally fertilised by the male.

Question:

Which examples (from the list above) of cartilaginous fish do we have in the aquarium? ______

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3. REEF FISH Reef fish make up the most spectacular elements of coral reefs around the world. The brilliant range of colours and patterns is believed to have developed for identification purposes. Many reef fishes are very territorial and distinct ‘poster-like’ colours are shown by the most aggressive species. Other reasons for specialised colouration are:

Counter shading where darker and lighter pigments appear on the upper and lower body respectively. This camouflages the fish when seen from above or below.

Disruptive shading distracts from the fish as a whole i.e. the false black ‘eyespots’ near the tail (e.g. Butterflyfish) and the eyes camouflaged by a black stripe (e.g. Butterflyfish, Moorish Idol, Angelfish etc.)

Cryptic colouration which blends the fish into the coral on which it lives (e.g. red hawkfish) or the substrate such as the poisonous stonefish.

Warning such as that of the red colouration lionfish could warn predators that the fish is poisonous and should be avoided.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 20 Coral reefs have the most species of fish in the world each adapted to specific foods for which the mouth, teeth, body shape etc has been developed to maximise their chance of survival. In the next illustration the different mouth shapes give an indication of some of the feeding habits of fishes. ( also look at page 8 and compare the mouth shapes to those illustrated on page 8)

Threadfin Butterfly fish. Coachman or longfin bannerfish. Widespread from Indo-Pacific to Mossel Bay. Widespread from Indo-west Pacific. Grows Grows to 20cm. to 16 cm. Feeds on small reef invertebrates Preys on small invertebrates.

Birdfish. Bluestreak Cleaner Wrasse. Found in Indian Ocean grows to 28 cm. Common and very active fish found in Indo- Colour varies with age and sex. Pacific southwards to Algoa Bay. Feeds on ectoparasites and mucous of other fish Feeds on small benthic (bottom dwelling) entering mouths and gill chambers if invertebrates and uses its long snout to necessary. Parasite-infected fish queue up remove prey from crevices for ‘cleaning service’ provided by these wrasse.

Emperor Angelfish. Powder-blue surgeonfish. Found from Sodwana to Indonesia and Found in Indo-pacific and grows to 40 cm. grows to 23 cm. Juveniles differ dramatically from adults in pattern and colouration. Feeds on seaplants. Feeds on sponges and other invertebrates.

Picasso triggerfish. Clown triggerfish. Found in the Indo-West Pacific area grows Found in the Indo-West Pacific area grows to to 30 cm. 30 cm. Omnivorous Preys on hard shelled invertebrates which it crushes with its teeth.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 21 4. PELAGIC FISH The ocean beyond the littoral zone is divided into two regions (1) Benthic – all plants and animals that live on or near the bottom (2) Pelagic – all plants or animals in the ocean that are not associated with the bottom.

Pelagic fish are fish that live in the open seas. Many species of pelagic fish migrate along the coast and breed in large numbers. Pelagic shoals are the main source of fish caught by trawlers and fish factories. Snoek, tuna and mackerel along with sardines, anchovies and herrings are commonly found in the sea around South Africa. Four species of pelagic fish found in the ‘Open Ocean’ or ‘Predator Exhibit’ at the Two Oceans Aquarium are: Cape Yellowtail (also called Albacore, or Amberjack). Grows up to 50 kg and occurs in large shoals in summer in False Bay down to Struisbaai. In winter they migrate to Eastern Cape and KwaZulu Natal following the annual pilchard migration. Geelbek (also called Cape Salmon) Grows up to 25 kg and occurs in large shoals at all times around the west coast although they migrate up to KwaZulu Natal in spring for spawning. It is a very aggressive fish and squid feeder. Elf (also called Shad) Can grow up to 12 kg but most usually around 1-2 kgs. An aggressive fish with razor sharp teeth that spawns in KwaZulu Natal from September to November. Maasbanker (also called Horse Mackerel) A spindle shaped silvery fish that grows up to 70 cm and is heavily fished around the South African coast. Spawns in late winter and spring and is preyed upon by seals and dolphins.

Task: 1. Find at least two examples of benthic (bottom dwelling fish) in the aquarium. ______

2. What is the national fish of South Africa?______

5. EELS Eels are long-bodied, snake-like fishes that are usually scale less and lack pelvic fins. The saying 'as slippery as an eel' refers to the copious supply of mucus that covers the body and makes them very difficult to grasp. Eels have many more vertebrae and fewer bones in the face and jaw than do other fish. These structural features are associated with their habit of hiding in holes and crevices or burrowing in the sand, but some species are pelagic and swim in the open ocean. Perhaps the best- known eels are the freshwater eels and the morays.

Breeding All eels, even the freshwater species, breed in the open ocean. They pass through a prolonged stage called a leptocephalus larva when they are flat, transparent and glassy, quite unlike the adults. The

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 22 larval stage, can last from a few weeks to a few years depending on the species (which migrates great distances in the ocean currents).

5.1 MORAYS The most conspicuous eels of the coral reefs are the morays, which are sharp-toothed, long- mouthed and successful predators. Morays often have distinctive patterning and colouring. In KwaZulu-Natal morays and rock lobsters often share a hole. If an octopus feels along the ledges in search of a lobster meal the moray darts out and catches the octopus instead.

Task: What kind of moray eels do we currently have on exhibit in the aquarium? ______

6. SEAHORSES

Seahorses are thought to have evolved at least 40 million years ago. They inhabit shallow seagrass beds in estuaries and warm coastal water. Feeding Seahorses feed on small, planktonic organisms that are sucked through their small mouths. Breeding Seahorses mate for life and are highly territorial. The female deposits her eggs (where they are fertilised) in the male's pouch, the soft tissues of which provide the eggs with the oxygen and nutrients. Pregnancy lasts between two and four weeks and during this period the female seahorse develops a new batch of eggs. As soon as the male seahorse has expelled his brood, the female will deposit another batch of eggs into his pouch.

Did you Know? 0 In the aquarium the temperature for the Knysna seahorse display is kept at 15 C to prevent them from breeding. We are not allowed to release the Knysna seahorses as the main threat to them currently is habitat destruction.

7. SUNFISH They are found in all, except the polar, oceans. The skin is thick and tough with small rough denticles, similar to a shark's skin. Although sunfishes lack a swim bladder, the fat stored in their tissues makes them light and buoyant. They have four gill arches and a single round gill opening on the side of the body at the base of the pectoral fins. The sunfishes have large mammal-like eyes and seem to rely on their eyesight for finding food and avoiding objects.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 23 Feeding The sunfish sucks jellyfish, salps and comb jellies (on which it feeds) into its small round mouth and then crushes them, using a parrot-like beak comprised of fused teeth.

Breeding The sunfish is the most fecund( fertile) of all fishes, producing nearly 300 million eggs that are shed into the sea during spawning. CONSERVATION THROUGH RESEARCH AND OBSERVATION

It is almost impossible to observe an animal throughout its life. Many fish are broadcast spawners shedding their eggs into the vast ocean and others have microscopic larval stages. Obviously it is equally difficult to find the same adults again and again. In the case of whales, helicopters are used to track individuals due to their distinctive markings but how could you distinguish between two yellowtails or two sea urchins? There are a few methods that have been used and they are described here:

1. Tagging There are three groups of animals that have been extensively tagged in South Africa either because they are easy to tag or because of their extensive exploitation and importance to the fishing industry. They are fish, rock lobster and molluscs. Tags have to be attached firmly, and survive moulting in the case of rock lobsters, to a suitable surface and the glue must stick underwater. The animal has to be recaptured to obtain a result and this is done by relying on the fishing industry, and the public. Not only do large numbers of animals need to be tagged to ensure some results (which is very costly), but also more education is needed to get total cooperation from all sectors.  Fish The Oceanographic Research Institute (ORI) encourages all angers to participate in their nationwide Tagging Programme. This involves anglers tagging and releasing their catches. All participating anglers receive feedback on the statistics they submit and a computerised report if their fish is recaught.  Rock lobster As they grow in spurts just after moulting and before the new shell has hardened, large numbers have to be tagged before they moult. A long plastic tag with a hook on the end is inserted between the thin joints of the shell and embedded in the muscle of the abdomen so that it is retained when the animal moults. Researchers rely on the rock lobster industry to return all tagged animals and provide reward incentives. Over 2000 rock lobsters are trapped and tagged annually. The recapture rate is high enough to provide information on growth rates for management of that stock.  Molluscs The most successful results are obtained from animals with shells on which to attach tags and those like limpets and abalone, which are slow moving and return to their home scars, can be found again and again. Squid have also been tagged with a ‘spaghetti tag’ embedded in the muscle.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 24 How the Aquarium assists with research and tagging process: Both sharks recently released have been tagged with internal acoustic tags. After anaesthetizing the sharks, the vet made a short incision (3-5cm) in each shark’s belly, inserted the tag into the abdominal cavity & sutured the cut. The tag itself is slightly shorter than a white board marker, about the same diameter and has a battery life of 10 years! These tags are made of a biologically inert material, meaning that it will not harm the shark in any way; it will stay inside the shark’s body for the rest of its life. The tag transmits a signature signal that is logged each time the animal passes by a specialized “listening” station. There are an array of these stations along the South African coastline -this means that we should get near-shore migration data on each shark for the next 10 years, helping scientists to track their movement, leading to better understanding of ragged-tooth shark migration, behaviour and population dynamics.

Here's an article Stuart from FLOW wrote for South African Tourism on the shark release, with a 3min video highlights package of the best bits from the two separate videos: http://blog.southafrica.net/blog/entry/doing- invaluable -work-for-shark-conservation or you can download the Youtube video of Kays release.

2. Aquaria or aquaculture farms Useful information can be provided from these sources but it needs to be compared to the natural environment. Only selected species can be grown successfully in captivity in sufficient numbers such as mussels and oysters. Rock lobsters have a complex and lengthy life cycle as larvae and this has meant that it is not yet viable to farm these animals despite the obvious rewards. Direct observations in aquaria have provided the following interesting facts: Anemones have been known to live for 100 years in aquaria. Seahorses born at the Two Oceans Aquarium have grown from 1cm to about 2cm in a single month. Mussels are successfully ‘farmed’ by aquaculture – and the black mussel can grow to 6cm in length in about 6 months reaching 9cm in a year. Abalone (perlemoen) grows slowly once the larvae settles after 3-6 days. After 5 months in aquaculture they are only 5mm, after 5 years about 8cm and at 13 years reach 11+cm, which is the legal size for harvesting. Note that shells of 18cm are about 30 years old! Octopuses are short lived and die after about a year when their eggs are hatched. Tropical fish have been bred for many years and a great deal of information has been amassed about them.

Did you know: Fertilised kob and yellowtail eggs removed from the I & J Predator exhibit has been cultured in the Seapoint research aquarium to assist with establishing aquaculture of these species.

3. Growth rings Several methods have been explored using the idea of growth rings, much like those in a tree trunk. The principle is that certain substances are laid down at different rates under different conditions experienced seasonally, monthly or daily – which create alternating thick and thin layers seen as rings. Remarkable results have been obtained from two groups of animals – fishes and corals.

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Fish otoliths Otoliths are the ear bones of fishes. These bones move in a pocket of sensory cells which record their position and give the fish information about balance, determine its orientation and speed of turning. Otoliths are distinctive for different species of fish and have summer and winter growth zones laid down each year, which are best seen when a thin section is taken from the otolith and polished. Some fishes lay down two rings a year so the zones need to be verified against fishes of known ages. A chemical, tetracycline is injected into a fish to stain the current ring on the otolith. So, if the otolith is collected a year or two later, the number of rings laid down since the tetracycline staining can be counted. Information from otoliths has been used extensively to age fish and even those otoliths recovered from predators can provide an insight into the species and age of their prey. Obviously the big disadvantage is that only a dead fish can provide this information!

Corals Stony coral skeletons record not only annual growth rates, but also monthly and daily rates. This is because the calcium deposited is affected by temperature, tides and sunlight. The living coral houses micro-algae in its flesh, which photosynthesises, provides food and assists in the deposition of calcium during light hours.

4. Year Group Analysis This method can be used where the animals occur in fairly dense established populations – especially useful for an animal like the sea urchins is that it is difficult to label! It gives the best results in animals with distinct spawning times, preferably once a year. Either - ALL the animals in a FIXED AREA are measured or a FIXED number of animals are measured. This needs to be repeated at intervals during the year. The population shows distinct size groups called cohorts, which correspond to larval settlements. Scientists need to determine what these peaks correspond to – are they annual, biannual or even monthly peaks. The gonads can be examined by dissection through the year to determine when the animals spawn. When possible the peaks can be correlated with results from tagging. The population can also be measured throughout the year to see how the cohorts grow and how long it takes for cohort 1 to reach the original size of cohort 2 for example.

CONSERVATION VERSUS ECONOMIC FISHING INDUSTRIES 1. OVERVIEW Over the last century the fishing industry has undergone major changes. Before the early 1900’s no large-scale fishing existed worldwide however this is not the case today, with fishing fleets roaming the oceans and removing huge quantities of fish. In South Africa several factors have to be considered when considering how to sustain our valuable fish stocks. 2001 Government announces tough new angling limits1. The measures will follow the recent declaration of a fishing ‘state of emergency’ by Environment Minister Valli Moosa. Similar measures are being laid down by the United Kingdom and the European Union. Several popular species have been pushed to the brink of collapse because of the pressure of too many anglers catching too many fish.

1 This article appeared in March 2001 by Bruce Mann and Independent Newspapers and highlights the current thinking on fishing. Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 26 Full details of the new line-fish conservation measures have not been announced yet, but officials have published a list of at least 20 key species, which are considered to be dangerously overexploited or seriously threatened. Yet fish harvesting by humans this century has reached alarming, unsustainable levels. As recently as the 1930’s the total world catch of fish and shellfish was less than 20 million tons a year. But by 1970, this catch climbed to 70 million tons because of human population growth and improved fishing technology, such as echo sounders to locate shoals, and more sophisticated freezing techniques. And locally, fishing competitions have increased the pressure. It is inevitable that there would be protests when the new regulations are announced. But if dwindling fish stocks are to be protected for present and future generations, the only options are either to restrict the number of fishermen or to limit their catches. It is believed that recreational or ‘sport’ fishermen will still be able to enjoy their sport. According to the DEAT (Department of Environmental Affairs and Tourism) there are now about 3 000 commercial fishing boats, more than 3 500 recreational ski boats, 400 000 shore anglers and an unknown number of subsistence fishermen - all chasing a limited pool of about 200 fish species. The 2800 commercial licences are likely to be cut by more than two thirds to 450 traditional line-fish vessels, 130 hake hand-line boats and 200 tuna vessels. Recreational bag limits for some fish could also be cut from five fish a day to just one or two a day, while in some cases (e.g. dusky kob) a night-time ban on recreational fishing has also been recom- mended. Limited Users On the basis that open access to all is not an option, different controls are appropriate means of limiting catches and methods of control need to be tailor-made for each stock. When rights to fish are allocated, issues such as transferability of rights, length of time of these rights, payments for the rights and methods used to allocate the rights fairly are all critical. Rules and regulations regarding the capture of fish are promulgated under the Living Marine Resources Act 1998. Economic Efficiency Any system that is put in place must be economically efficient as the fishing industry provides employment and a means of survival for many people and yet the sustainability of the fish resources must not be put in jeopardy. At present the government has not agreed with the European Union which has requested that South Africa grant fishing rights to EU trawlers within her territorial waters. As studies in Namibia have shown that foreign fishing vessels do not adhere to a quota system and it is very difficult to monitor their movements.

How do Marine Reserves benefit Marine Life?  Protects them from urban development and human pressures and provides shelter for threatened species.  Population densities of larger species that are normally exploited by fishermen are enhanced.  Provides breeding refuge from exploitation and better balance of marine ecology.  Protects habitat and helps recovery of damaged areas.  Easier to police than other management methods such as bag and size limits and closed seasons.  Some species need extra protection when spawning.  Protects from pollution. How do Marine Reserves benefit humans?  Creates recreational facilities and commercial ventures.  Enables observation and study.  Valuable tourist asset for the eco-tourist, providing an opportunity of seeing endemic species in their natural habitat.  Job creation for tribal people living on the land and fishermen can use their knowledge to educate visitors.

Two Oceans Aquarium Volunteer Manual – MODULE 5 -- FISH Page 27  Enhance certain species in adjacent areas e.g. Galjoen at de Hoop nature reserve.  Act as seeding ground for adjacent exploited areas. Conclusion Heavy fines or penalties should be implemented for exploitation of all forms of marine life, and also beach vehicles that cause damage to sand dunes and sand dwelling plants and animals. Community involvement will promote job creation and general upliftment of their everyday life e.g. curio shops etc. Without Marine Reserves, the country could end up with a devastated coastline and nothing for future generations to learn from or to observe. 2. STATUS OF CERTAIN FISH STOCKS IN 2001

1. DUSKY KOB Status: Collapsed. Recommendation: Increase size limit from 40 cm to 60 cm; reduce daily bag limit from five fish to one; ban recreational night fishing; reduce commercial effort by 70%. 2. SQUARETAIL KOB Status: Collapsed. Recommendation Increase size limit from 35 cm to 40 cm, bag limit unchanged pending further research; reduce commercial effort by 70%. 3. GEELBEK Status: Collapsed. Recommendation: Reduce daily bag limit from 10 fish to two; ban recreational night fishing; reduce commercial catch effort by 50%. 4. SEVENTY-FOUR Status: Collapsed. Recommendation: Maintain current fishing ban for at least 10 years. 5. SLINGER Status: Collapsed. Recommendation: Reduce commercial effort by 50%. 6. RED STEENBRASS Status: Collapsed. Recommendation: Increase Size limit from 40 cm to 60 crn; reduce bag limit from two to one; reintroduce a closed season from September 1 to November 30. 7. YELLOWBELLY ROCK COD Status: Collapsed. Recommendation: Reduce bag limit from five to one; and possibly increase size from 40 cm-60 cm. 8. CATFACE ROCK COD Status: Collapsed. Recommendation: Possibly increase size limit from 40 cm to 50 cm and extend current bag limit of five fish per day to include commercials. 9. SCOTSMAN Status: Collapsed. Recommendation: Increase size limit from 30 cm to 40 cm; reduce bag limit from five fish to one. 10. ENGLISHMAN Status: Overexploited. Recommendation; Reduce commercial effort by at least 50%; reduce recreational daily Bag limit from five fish to one and introduce a minimum size limit of 40 cm. 11. POENSKOP Status: Collapsed. Recommendation: Reduce bag limit from two fish to one for commercials and recreationals. 12. STREPIE Status: Under exploited. Recommendation: Move strepie from ‘bait list’ to ‘exploitable list’ and introduce a daily bag limit of 10 fish as a precautionary measure 13. ELF (SHAD) Status: Overexploited. Recommendation: Reduce daily bag limit from five fish to four; reduce closed season by one month; consider listing it as a recreational fish only, with concessions to some commercial fishers. 14. KING MACKEREL Status: Overexploited. Recommendation: Maintain current restrictions pending further control measures in Mozambique. 15. QUEEN MACKEREL Status: Optimally exploited. Two Oceans Aquarium Recommendation:Volunteer Manual – MODULE Maintain 5current -- FISH restrictions pending furtherPage 28 control measures in Mozambique. REFERENCES

Bond, C.E. 1979. Biology of Fishes. London: Saunders College Publishing. Bruton, M.N. 1995. Questions & Answers: Sea Fishes of Southern Africa. Cape Town: Struik. Lagler, K.F., Bardach, J.E. Miller, R.R. & Passino, D.R.M.. 1985. Ichthyology. London: Wiley. Paxton, J.R. & Eschmeyer, W.N. (eds). 1994. Encyclopedia of Fishes. Sydney: University of New South Wales Press. Skelton, P.H. 1993. A Complete Guide to the Freshwater Fishes of Southern Africa. Halfway House: Southern Book Publishers. Smith, M.M. & Heemstra, P.C. 1988. Smiths' Sea Fishes. Halfway House: Southern Book Publishers. Van der Elst, R.P. 1988. A Guide to the Common Sea Fishes of Southern Africa. Cape Town: Struik. Van der Elst, R.P. & Denis King 2000. Everyone’s Guide to Sea Fishes of Southern Africa. Cape Town: Struik. Norman, J. R. A History of fishes. Ernest Benn Limited, London Steven Hall, Your Healthy Garden Pond. A supplement to Essential Water Garden. Aceville Publications Ltd, Britain.

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