Research Journal of Animal, Veterinary and Fishery Sciences ___________________________ ISSN 2320 – 6535 Vol. 1(8), 12-18, September (2013) Res. J. Animal, Veterinary and Fishery Sci. Review Paper Overviews on Diversity of Fish Pandey Govind Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, Rewa (Nanaji Deshmukh Veterinary Science University, Jabalpur), MP, INDIA Available online at: www.isca.in Received 2nd May 2013, revised 1st August 2013, accepted 11 th September 2013 Abstract Fish have great diversity and hence they can be classified in different categories. “Fish” generally refer to several aquatic animals but actually all of them are not fish, such as starfish, shellfish, cuttlefish, jellyfish and crayfish. Jawlesh fish are the most primitive fish. In deed, the ancestors of cartilaginous fish (having a cartilaginous skeleton) were the bony animals and they developed paired fins firstly. Bony fish are categorized into the lobe finned and ray finned fish. Teleost fish are the most ‘modern’ (advance). As regard to size, Paedocypris progenetica is the smallest fish. Gobies have the shortest life span and they are small coral reef-dwelling fish. Only 58% of extant fish are salt water, while a disproportionate 41% are fresh water fish and remaining 1% is anadromous fish. Groupers are protogynous hermaphrodites, who school in harems of 3 to 15 females. Fish adopt a variety of strategy for nurturing their brood, e.g., shark differently adopts three protocols with brood. Many fishes are food opportunists or generalists as they eat whatever they get easily. Fishes with four eyes have eyes above the top of head which are divided in two different parts, so that the fish can see below and above the water surface simultaneously. Seahorses are the slowest-moving fishes. So called the ‘toxic fishes’ are able to produce strong toxins in their bodies. Moreover, there are commercial food fish, recreational sport fish, decorative aquarium fish and tourism fish. As the most vertebrate species have brain-to-body weight ratios, fish also have the relative brain weights of vertebrates. Keywords: Fish, fish diversities/categories, fish species. Introduction (rarely three) dorsal fins, an anal fin and a tail fin. This also bears jaws and skin (that is usually covered with scales), and “Fish” denotes any non-tetrapod craniate (an animal with a skull lays eggs. There is exception in each of these criteria. For and mostly with a backbone) that has gills, and whose limbs (if example, tuna, swordfish and some species of shark show some 1 any) are fin-shaped . Unlike mammals or birds, fish are not a warm-blooded adaptations. They can heat their bodies clade but they are a paraphylectic collection of taxa, including significantly, and their streamlining and swimming performance jawless, skeletal and cartilaginous types (e.g., hagfish, lampreys, varies from fish (e.g., tuna, salmon and jacks that can cover 10- 2-3 sharks and rays, ray-finned fish, coelacanths and lungfish) . 20 body-lengths/second) to species (e.g., eels and rays that swim The lungfish and coelacanths are closer relatives of tetrapods not more than 0.5 body-lengths/second) 1. Several groups of (e.g., mammals, birds, amphibians) than the other fish (e.g., ray- freshwater fish take oxygen from air and water with the help of finned fish or sharks). So, the last common ancestor of all fish is different structures in them. The lungfish have paired lungs like also an ancestor to tetrapods. However, the paraphyletic groups those of tetrapods, and gouramis have ‘labyrinth organ’ that do are no more in modern systematic biology, so the term “fish” as similar functions; however, many catfish (e.g., Corydoras ) take a biological group must not be used. oxygen through the stomach or intestine 4. “Fish” generally refer to several aquatic animals but actually all The fins have very variable body shape and arrangement, of them are not fish, such as starfish, shellfish, cuttlefish, showing un-fishlike forms of anglerfish, gulpers, pufferfish and jellyfish and crayfish. During 16 th century, though the biologists seahorses. Similarly, the fish skin surface can be naked (as seen did not make a distinction, the natural historians classified also in moray eel) or it may be covered with scales known as placoid seals, whales, amphibians, crocodiles, even hippopotamuses and (typical of shark and ray), ganoid (different fossil fish but also a host of aquatic invertebrates, as the ‘fish’. But as per the living gars and bichirs), cosmoid (fossil lungfish and definition of “fish”, all the mammals, including Cetaceans (e.g., coelacanths), cycloid and ctenoid (last two are found on most whales and dolphins) are not fish. Particularly in aquaculture, bony fish). Many fish still live on land. The mudskippers feed the true fish are called “finfish” (or fin fish) to differentiate and interact with one another on mudflats, and go underwater to them from other animals. An ecothermic fish has a streamlined hide in their burrows 1. Phreatobius cisternarum (catfish) lives body for rapid swimming that extracts oxygen from water by underground, and in phreatic habitats, and its relative lives in using gills or that uses an accessory breathing organ to breathe waterlogged leaf litter 5-6. Furthermore, there are many different oxygen. This fish has two sets of paired fins, usually one or two shapes and sizes of fish. The whale shark may have the large International Science Congress Association 12 Research Journal of Animal, Veterinary and Fishery Sciences ________________________________________ ISSN 2320 – 6535 Vol. 1(8), 12-18, September (2013) Res. J. Animal, Veterinary and Fishery Sci. size of about 17 m (52 ft), while the stout infant fish may have Cartilaginous fish: They have a cartilaginous skeleton; the tiny size of about 8 mm (0.3 inch) 1. however, their ancestors were bony animals and were the first fish to develop paired fins. The cartilaginous fish do not have Fish have great diversity and hence they can be classified in swim bladders. Their skin is covered in placoid scales (dermal different categories. Though fish species have been discovered, denticles) which are as rough sandpaper. Because cartilaginous about 250 new ones are still discovered every year. As per the fish do not have bone marrow, the spleen and special tissues data of FishBase, 32,100 fish species had been described by around the gonads produces red blood cells (RBCs). Their tails September, 2011. This is more than the combined total of all can be asymmetric, with the upper lobe longer than the lower other vertebrates, i.e., mammals, birds, amphibians and reptiles 1. lobe. Some cartilaginous fishes possess an organ called Now a days, the documentation of biodiversity has become very “Leydig’s organ”, which also produces RBCs. There are over important aspect of science due to various environmental 980 species of cartilaginous fishes. They are sharks, rays and influences. Fish diversity of any regime has great significance in chimaera 1. assessment of that zone reference to environment and pollution, as well as it contributes to the necessary information for Bony fish: They include the lobe finned and ray finned fishes. fisheries. Many fish species may be the bio-indicators as well 7. The lobe finned fish is the class of fleshy finned fish, consisting The fish diversity of Mahanadi river suggests that this river is of lungfish and coelacanths. They are bony fish with fleshy, endowed with a variety of endemic fish species. Number of lobed paired fins, which are joined to the body by a single bone. these fish species are significantly considered ornamental These fins evolved into the legs of the first tetrapod land species. The economic potential of these ornamental fishes may vertebrates, amphibians. Ray finned fish is so-called because it be used for the domestic market in the first place for aquarium possesses lepidotrichia or ‘fin rays’; its fins being webs of the purpose 8. Now, there is a great need to adopt rational methods skin supported by bony or horny spines (‘rays’). There are three and new technology in the fishing towards the conservation of types of ray finned fish: chondrosteans, holosteans and teleosts. fish diversity of several rivers like Mahanadi. A few effective The chondrosteans and holosteans are primitive fishes sharing a measures have been suggested for this purpose. The mixture of characteristics of teleosts and sharks. The holosteans management measures aimed at conserving freshwater fishes are closer to teleosts and further from sharks in comparison with should be part of fishery policies of Governments. The the other chondrosteans 1. broodstock maintenance centres and hatcheries should be established exclusively for endangered and critically endangered Teleosts: They are the most advanced or ‘modern’ fishes. They indigenous fishes for their in situ conservation. Investigation of are overwhelmingly the dominant class of fishes with nearly invasive nature of exotic fish species in the natural habitats 30,000 species, covering about 96% of all extant fish species. should be done to establish the nature of their natural breeding They are ubiquitous throughout the freshwater and marine populations and the extent to which their feed habits overlap environments from deep sea to the highest mountain streams. with endemic population of fish 8-11 . They include nearly all the important commercial and recreational fishes. Teleosts have a movable maxilla and Diversity of Fish premaxilla, and corresponding modifications in the jaw musculature. These modifications make it possible for teleosts According to Species: to protrude their jaws outwards from the mouth. The caudal fin Jawless fish: They are the most primitive fish. There is debate is homocercal, meaning the upper and lower lobes are about whether they are really fish or not. The jawless fish have no jaw, equal in size.