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.