JIGS Vol. 2 No. 4 July 2003 The Journal of the Round Gobies in Captivity International Goby Society Before working with live round gobies, consult local state or Vol. 2 No. 4 July 2003 provincial laws. In North America, it is generally illegal to possess live round gobies, either as bait or for aquarium use. The reason for these laws is to prevent accidental or inten- tional introductions to areas where they do not yet occur. However, if you would like to see captive round gobies, they may be observed at public aquariums such as the Shedd Aquarium in Chicago, Illinois.

Patricia Arseneault lives in Windsor, Ontario and is a wildlife rehabilitator for the Canadian Ministry of Natural Resources. Someone turned in a live round goby to her organization, which she kept in a 75 gallon community aquarium. (This was legal because of her state permit - assuming of course, that she not release the goby.) She found the new acquisition to be a delightful and endearing aquarium specimen; easy to feed with flake food, frozen brineshrimp and bloodworms. She was most highly impressed by its awareness to its surroundings, ability to recognize her as a food source, and ability to change color and pattern rapidly.

She wrote: “When I first received him, he was a light olive green with a very striking darker pattern (similar to the check- erboard pattern on a fox snake). My tank bottom is sand with tons of plants. Within a few hours of placing him in the tank, he changed to a light brown with a green undertone and the pattern was pretty well gone. It happened so fast I wasn't even sure afterward that he had been a different color.”

Unfortunately, an electrical mishap caused an early demise to some of Pat’s favorite fishes, including her round goby.

20 JIGS Vol. 2 No. 4 July 2003 JIGS Vol. 2 No. 4 July 2003 Why Control Round Gobies? ISSN 1543-7744 ————————————————————————– There are at least two major potential problems with the round goby’s presence in the Great Lakes. One is their competitive The Journal of the International Goby Society (JIGS) is the advantage over native species. Round gobies are more quarterly publication of the International Goby Society (IGS). efficient feeders and also more aggressive than native darters Non-profit organizations may reprint articles, however we ask and sculpins. The also reproduce more quickly. Unlike that you contact the editor before doing so. native sculpins, female round gobies spawn more than once per season. In some places, they have been shown to reduce Editor: Naomi R. Delventhal the populations of these small native fishes. [email protected] or [email protected] Another major problem of round gobies is their affect on the International Goby Society, P.O. Box 329, Richland Center, food web. As I mentioned earlier, round gobies are efficient WI 53581, USA consumers of zebra mussels. Larger fish eat round gobies, ————————————————————————— which sounds like a good situation, since zebra mussels are Our scientific advisors: not usually available in useable form to native fishes. Dr. Helen K. Larson Indo-Pacific and Australian Gobies Unfortunately, this may cause serious problems because zebra Dr. Richard Winterbottom Indo-Pacific Reef Gobies mussels are filter feeders that take in large quantities of fine Dr. James L. Van Tassell Atlantic and Eastern Pacific Gobies suspended material. Pollutants (such as mercury and PCBs) Dr. Robert A. Patzner Mediterranean Gobies ingested by these mollusks build up in the bodies of the round ————————————————————————— gobies and are further concentrated in the piscivorous fish that Contents eat them. Eventually these pollutants may be taken in by water birds or humans that eat the larger fish.

Editor’s Introduction……………………………………….3 Because of these negative effects, most ecologists and

fisheries biologists believe it is important that the round goby Goby Queries………………………………………………4 not spread to other areas - particularly the Mississippi river

and its drainage basin. Mudskippers: The Periophthalmus species, Part 3………..9

By Richard Mleczko For more information on round gobies, including many

technical papers from which information for this article was The Round Goby…………………………………………..13 drawn, visit the Sea Grant Nonindigenous Species Site: By Naomi Delventhal http://www.sgnis.org/update/goby.htm

2 19 JIGS Vol. 2 No. 4 July 2003 JIGS Vol. 2 No. 4 July 2003 Editor’s Introduction Life History of the Round Goby

In both their native and introduced habitats, round gobies This issue marks the end of the second year of JIGS, and looking typically migrate to deeper water during the winter and back it has been a very interesting experience being editor. But it shallow water during the spring to spawn. Each female takes much more than an editor to make a good newsletter. I am indebted to all of my readers - both gobiologists and aquarists - spawns several times per season; males select cave-like for comments, questions, articles, and for simply reading this structures as nests. Males attract the females by a mating call modest publication. It’s not always easy to publish a goby news- - not what most of us usually expect of a fish, although round letter, and sometimes I wonder how I manage to balance it with gobies are not unique in this regard. Males take on a dark family, friends, 20 tanks of gobies, and my education. I thank all coloration during breeding season, when they are of you readers for your support - and for helping to make the spawning and guarding eggs. It is thought that the males die International Goby Society and this publication a reality. after one breeding season. Naomi Delventhal 31 July 2003 Round gobies lay large (about 3.5 mm) eggs which hatch in 2-3 weeks, depending on temperature. Unlike with most —————————————————————————— gobies, there is no planktonic larval stage - the newly hatched Cover photos: (Top) Gobiodon rivulatus, with its host coral. fry are already more than half a centimeter long and Photo by Phil Munday. (Bottom) Gobiodon histrio, in immediately hop about on the bottom like the adults. They aquarium. Photo by Takahiko Mukai. stay in the nest, however, for a few days before moving on. Regarding the mix-up of the two species, Rick Winterbottom, Round goby development before hatching is indeed amazing. who studies Gobiodon taxonomy, explains the history: “The While still an embryo, the goby’s digestive system becomes confusion of G. rivulatus with G. histrio (a later name, and valid) functional, and while in the egg it actually swallows yolk came about because in the original description of G. rivulatus, material, digests some of it, and excretes the remainder! No Rüppell stated that it was green with red bars - and juveniles can be that, although I have never seen a green and red adult. This other gobies are reported to have such a development. was picked up by Jack Randall, who identified his photo of G.

histrio as G. rivulatus in his book on Red Sea fishes (both occur Round gobies are primarily carnivores that consume a range there). But Tony Harold has examined Rüppell’s type specimens of bottom dwelling organisms - including insect larvae, of G. rivulatus, and they are the species with wavy thin bars on crustaceans, small fish, fish eggs, and mollusks. This last the head and the body. I went back to Rüppell’s original descrip- item is especially important in their diet, because round tion (in German), and the translation relating to the colour pattern gobies are efficient predators of another nonindigenous reads: ‘Ground colour of whole body emerald green, with a car- nuisance species, the zebra mussel. min-red labyrinth-like pattern of lines, all fins grass-green.’ So you can see how easy it is to go wrong!”

18 3 JIGS Vol. 2 No. 4 July 2003 JIGS Vol. 2 No. 4 July 2003 Goby Queries

Q. I really like clown gobies, and want to set up a tank just for them. Should they be kept with live corals? If I keep the red, green, and yellow ones together will they hybridize? Can they be bred easily in captivity, like neon gobies?

A. The variously colored coral gobies (Gobiodon spp.) are comprised of 16 valid species, with several additional species awaiting formal description. Most aquarium dealers in the USA sell them as inexpensive beginner’s fishes, lumping them all together under the name “clown gobies.” This lack of at- tention is a pity, since they are a fascinating group of reef gobies. Species I’ve seen offered for sale include G. axillaris (brownish with somewhat indistinct red bands on the head), G. citrinus (various shades of yellow to almost black with narrow, well-defined “electric blue” bands on the head and similarly colored stripes at the bases of the dorsal and anal fins), G. histrio (green with wide red bands on the head and red stripes/spots on the body), G. okinawae (bright yellow with no stripes or bands), and G. quinquestrigatus (red with pale, narrow vertical lines on the head and a darker body and fins). G. rivulatus is similar to G. quinquestrigatus, but has narrow wavy lines on the body, as well. This species has been confused with G. histrio (see note under introduction). Other species may also show up from time to time in the trade.

In nature, these small, highly compressed gobies are usually Above: Inside of the Round Goby Watch Card, an example of associated with branching corals of the genus Acropora. If the efforts being made to increase public awareness of the you are a skilled reef aquarist, a coral set-up is possible, round goby’s presence as an invasive species. although the gobies may irritate the corals by constantly sitting on them and there is some evidence that the natural All images used by permission of Minnesota Sea Grant. diet includes tissue from the host coral itself. Otherwise, the

4 17 JIGS Vol. 2 No. 4 July 2003 JIGS Vol. 2 No. 4 July 2003 Gobiodon okinawae, the most popular of the coral gobies in the hobby. Compared with other Gobiodon species, they are bolder and more likely to live in groups. Photo by Takahiko Mukai.

fish should be provided with artificial corals, coral skeletons, or branching type rock. These gobies will learn to accept a Top: Cover side of the Round Goby Watch Card, which is range of small drifting foods, but if they seem reluctant to eat often displayed in libraries and distributed free by Sea Grant at first, they should be offered live brineshrimp. in the Great Lakes region. Below: Back side of the Round Goby Watch Card, showing It’s not easy to say whether different Gobiodon species would how to identify round gobies. hybridize in aquaria. I have never heard a report of this happening and no hybrids have yet been identified in the wild. Coloration is usually important in goby courtship, and most Gobiodon species are distinct in coloration. According to Phil Munday, who studies the ecology of these gobies, another thing working against hybridization in the field is that species of Gobiodon have distinct patterns of habitat use (i.e. which coral colonies they inhabit), which means some species combinations are unlikely to ever occur in nature. Further- more, a number of species might prefer the same species of corals but it is uncommon to find mixed species groups. This means the opportunities for interbreeding are not great. For example, G. histrio and G. axillaris both prefer to live in Acropora nasuta but you rarely find them in the same coral colony even in places where both species are very abundant.

16 5 JIGS Vol. 2 No. 4 July 2003 JIGS Vol. 2 No. 4 July 2003 There only is one species, G. unicolor, that is commonly found to inhabit coral colonies with other species of Gobiodon. The tubenose goby (Proterorhinus marmoratus), a smaller goby species (endangered in the Black and Caspian Seas) has Like many other reef fishes, these gobies are hermaphrodites, also recently been found in the St. Clair River. However, it and several species have been shown to be capable of sex has not spread as quickly as the round goby, and being a less change in both directions. In most species there is one aggressive fish, has not caused as much concern among mature breeding pair per coral colony, with immature fish ecologists and fisheries biologists. being females. The ability to change sex is advantageous to the wild gobies - if one of a pair dies, the remaining individ- In North America, round gobies are often found in habitats of ual does not need to travel as far to find another potential larger stones and rubble. In Chicago, Illinois, I observed mate, thus reducing the risk of predation. numerous round gobies in rocky areas less than a meter deep. Local fishermen reported that they are easy to catch if bait is The ability of Gobiodon to change sex is also advantageous to allowed to sink. In some parts of their introduced range round aquarists who wish to breed them in captivity, since gobies are extremely abundant, but in other areas maintain (theoretically, at least) any two fish will become a male- only low populations. In Green Bay, Wisconsin, I fished for female pair. In captivity they can be kept either as pairs or in round gobies but did not catch any (only one was reported a harem, although in some species only the dominant pair caught in the bay during the three days I was there). But spawns. Coral gobies reproduce readily in aquaria, laying farther north in Sturgeon Bay anglers catch so many round their eggs on corals (or in the absence of corals, on rocks, or gobies they find them quite annoying! even on the aquarium glass). Raising the young is another matter. The larvae are small and the best rearing success has Interesting Facts About the Round Goby been reported using large, microalgae filled tanks and rotifers as first food. Like many other gobies, the round goby has fused pelvic fins and lacks a swim bladder. It therefore maintains a bottom Q. What can you tell me about sexual dimorphism in dwelling lifestyle, generally resting on the substrate. Also typical of gobies, it has a canal system on the head, but only bumblebee gobies? Also, I’ve been using “aquarium grade” superficial neuromasts on the body (instead of a true lateral rock salt for their water, but guessing at the quantities. How line where the neuromasts are enclosed in a canal system). much (spoonfuls or weight) per 10 gallons? I’ve recently This sensory system is ideal for night feeding, and helps give added a “dragon fish” (Gobioides broussoneti). The only info the round goby a competitive advantage over native benthic I can find says they’re from North America (where?), grow to fishes with similar habitat needs, including sculpins (family 19 inches and eat worms, etc. Anything you can add? Cottidae) and darters (Etheostoma and Percina spp.). It is J.R. Erickson large for a goby, with the maximum size reported about 30 Gavilan Hills, California cm, but usually remains significantly smaller.

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Stowaway! A. The most reliable way to distinguish the male and

female of most goby species (including bumblebee gobies) is The round goby is native to Eurasia, where it is found in areas by observing the shape of the urogenital papilla. This small of the Caspian Sea, the Black Sea and other bodies of water structure is located just after the vent and in front of the anal including larger rivers. It has a high tolerance for a range of fin. In males, it is pointed and often curved; in females it is environmental conditions such as salinity and temperature. In shorter, thicker, and blunt. Unfortunately, it is not always many parts of its native range, the waters have become highly easily visible until spawning time is near. In female bumble- polluted due to industry. bee gobies, the developing eggs are often visible through the

yellow band on the belly, and a highly gravid female is easy to Like many other invasive aquatic species, the round goby is identify. In my experience, the males of Brachygobius doriae thought to have arrived in the Great Lakes as an accident - in (the species most often sold) tend to be more orange in the this case, as a stowaway in the ballast water of ships traveling yellow bands, while the females are paler yellow. During from Eurasia, probably during the late 1980s. The fish (or courtship, the dark bands of both sexes become pale, leaving their eggs) most likely were taken in with the ballast water of the male with an overall yellow-orange appearance, and the a transatlantic vessel, and survived the journey across the female looking faded yellow and gray. ocean to be dumped into a new habitat. As with other organ- isms, an obvious responsibility of individual round gobies is Regarding the ideal salt concentration for bumblebees, to survive and multiply, which is exactly what they did, B. doriae can survive in water that is entirely fresh to over 1/4 having found the new habitat to be quite suitable for both strength seawater. Usually, I prefer to keep them in the lower activities. range, since in nature they are found primarily in freshwater.

A little salt does help prevent disease, especially in softer In North America, round gobies were first captured in the St. water; 1-3 teaspoons per gallon is appropriate. Clair River (between Lake Huron and Lake St. Clair) in 1990.

Within a space of five years, the round goby had found its Gobiodes broussoneti (known by several common names, way to each of the five Great Lakes. What hastened the speed although “violet goby” is preferred) has a wide distribution of its spread is thought to be the same mechanism which brought it to North America in the first place. Ships traveling within the Great Lakes also take in large quantities of (sometimes goby-laden) water, discharging it in other locations along with its piscine passengers. The same year round gobies showed up in the St. Clair River, they were discovered for the first time in the Gulf of Gdansk in the Baltic Sea (Poland) - again showing their ability to establish themselves in new locations.

14 7 JIGS Vol. 2 No. 4 July 2003 JIGS Vol. 2 No. 4 July 2003 Gobiodes broussoneti is known by several names, including violet goby, dragon goby, and dragon eel. The Round Goby: When a Good Fish Ends Up In the Wrong Place

By Naomi Delventhal [email protected]

There aren’t any gobies native to my home state, Wisconsin. And, until a few years ago, we didn’t have any gobies at all in Wisconsin waters. This changed, however, when the round goby (Neogobius melanostomus) came to the Great Lakes. Now, in Wisconsin as well as the other states and provinces on the Atlantic side of the Americas, ranging from South that border the Great Lakes, the round goby has become a Carolina in the north to Brazil in the South. It has been permanent resident, and it is closely studied and monitored for known to grow to about 20 inches, but rarely exceeds 12 possible negative effects on native fishes. inches in captivity. Violet gobies do better in more strongly brackish water than do bumblebee gobies, about 1/3 strength In some of these Great Lakes areas, the word “goby” alone seawater. They also should be kept in cooler water (about means one thing – the round goby. In fact, the round goby’s 65—75 degrees); bumblebees do best at warmer temperatures infamous reputation has gone far beyond those places where it in the mid 80s. For these reasons they do not make ideal tank has colonized. Try doing an Internet search using Google, mates. and you will find more “hits” for the round goby than any other goby species. (This is in part due to the efforts of Violet gobies are best kept in larger (at least 48 inch) tanks agencies such as Sea Grant, which publicize information on with a soft, sandy substrate and rocks or pipes for burrowing. invasive species.) Probably the most common problem people have keeping vio- let gobies in captivity is starvation. Violet gobies don’t feed Biological invasions have been a normal part of history, but in by sight, but rather by shoveling the substrate for edibles and recent centuries they have increased in frequency because of gulping mouthfuls of water. In community tanks, the other human activities. It is unlikely that the round goby will cause fish usually find all the food before the violet gobies come out an ecological disaster on the magnitude of that caused by the of hiding. This can be prevented by feeding the violet gobies Nile perch in Lake Victoria in Africa. But what has made the after the lights have gone out. Violet gobies learn to eat a round goby a successful invader? And what will be the long range of sinking foods, but newly introduced individuals often term effects of its presence in the Great Lakes? These are fas- require blackworms. cinating and important questions, and we don’t have all the answers yet.

8 13 JIGS Vol. 2 No. 4 July 2003 JIGS Vol. 2 No. 4 July 2003 King, R.P. and M. T. Udo. 1997. Vegetational succession - mediated spatial heterogeneity in the environmental biology of Periophthalmus Bar- Mudskippers - barus (Gobiidae) in the estuarine swamps of Imo estuary, Nigeria. Interna- tional journal of surface mining, reclamation and environment, The Periophthalmus Species Volume11. Part 3

Steeger, H.U. and C. R. Bridges. 1995. A method for long-term measure- ment of respiration in intertidal fishes during simulated intertidal condi- Periophthalmus barbarus tions. Journal of Fish Biology, volume 47. By Richard Mleczko Udo, M.T. 2002. Trophic attributes of the mudskipper Periophthalmus barbarus (Gobiidae: Oxudercinae) in the mangrove swamps of Imo estu- [email protected] ary, Nigeria. Environmental Sciences (China), 14(4).

Udo, M.T. 2002. Morphometric relationships and reproductive maturation of the mudskipper Periophthalmus barbarus from subsistence catches in the mangrove swamps of IMO estuary, Nigeria. Environmental Sciences (China), 14(2).

Udo, M.T. 2002. Intersexual plasticity in aspects of the biology of the mudskipper Periophthalmus barbarus (Gobiidae) in the mangrove swamps of IMO Estuary, Nigeria. Environmental Sciences (China), 14(1).

Photo by Richard Markham

Species identification: Linnaeus 1766.

Species name: The name barbarus is from the Greek barbaros, meaning foreign, possibly referring to the marked differences between this species and other gobies. P. barbarus in captivity. Photo by Marli Tanobe About the Author Other used names: Gobius barbarus, Gobius koelreuteri, Richard Mleczko is a hobbyist who knows what he’s talking Periophthalmus koelreuteri, Periophthalmus papilio, about. Visit his Mudskipper and Goby Website at Periophthalmus papillon, Periophthalmus gabonicus, http://members.ozemail.com.au/~thebobo/goby.htm Periophthalmus erythronemus.

12 9 JIGS Vol. 2 No. 4 July 2003 JIGS Vol. 2 No. 4 July 2003

Common names: Atlantic ————————————————————————— mudskipper, Butterfly mud- Periophthalmus barbarus featured in the literature. skipper, Tokouintokouin Compiled by Richard Mleczko (Benin), Adi, Soetsi, Lamole (Ghana). Etim, L., T. Brey and W. Arntz. 1996. A seminal study of the dynamics of a mudskipper (Periophthalmus papilio) population in the Cross River, Nigeria. Netherlands Journal of Aquatic Ecology, 30(1). Distribution: Known only from West Africa; Gambia, Etim, L, R.P. King and M.T. Udo. 2002. Breeding, growth, mortality and Senegal, Benin, Nigeria, An- yield of the mudskipper Periophthalmus barbarus (Linneaus 1766) gola and the Gulf of Guinea (Teleostei: Gobiidae) in the Imo River estuary, Nigeria. Fisheries Re- Islands. Photo by Marli Tanobe search, 56(3).

King, R.P. 1996. Population dynamics of the Mud Skipper Periophthalmus Distinguishing features: One of the only two Periophthal- barbarus (Gobiidae) in the Estuarine Swamp of Cross River, Nigeria. mus species to have blue in the first dorsal fin. Brilliant blue Journal of Aquatic Sciences, volume 11. spots on face and some blue vertical stripes on the body. King, R.P. and M. T. Udo. 2001. Fecundity of the mudskipper Pe- riophthalmus barbarus (Gobiidae) in Imo River, Nigeria. Archive of Fish- Physical characteristics: Typical ery and Marine Research, 49(2). length range 10 to 20 cm. First dorsal fin has 10 to 14 spines, second dorsal King, R.P. and M. T. Udo. 1998. Dynamics in the length-weight parame- fin has 11 to 14 elements. Anal fin ters of the mudskipper Periophthalmus barbarus (Gobiidae), in Imo River has 9 to 11 elements. estuary, Nigeria. Helgolander Meeresuntersuchungen, 52(2).

King, R.P. and M. T. Udo. 1998. Ovarian morphogenesis, breeding cycle Sexual dimorphism: The genital pa- and fecundity of the mudskipper Periophthalmus barbarus in the Imo pilla is broader and the free end more River estuary, Nigeria. African Fishes and Fisheries Diversity and Utilisa- rounded in females, on average the tion, FISA, Grahamstown, South Africa. The pelvic fins of height of the first dorsal fin is greater P. barbarus King, R.P. and M. T. Udo. 1998. Seasonality in diet and foraging per- in males. formance of the mudskipper, Periophthalmus barbarus (Gobiidae) in the Imo River estuary, Nigeria. Fish and Fisheries of Southeastern Nigeria. Aquarium suitability: Very good, most often exported to Europe and the United States. King, R.P. and M. T. Udo. 1997. Some aspects of the reproductive biol- ogy of the endangered mudskipper, Periophthalmus barbarus (Gobiidae), in Imo River estuary, Nigeria. Trans. Nig. Soc. Biol. Conserv, Volume 50.

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