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| ARTICLE INFORMATION Author:
Steve Smith |
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Ilyodon furcidens by Steve Smith Ilyodon furcidens is a member of the Goodeid family of livebearers. They resemble a shiner in appearance and they are sizeable, reaching three inches as adults. While most wild type livebearers are a nondescript dull gray color, the Ilyodon furcidens are very attractive with subtle yellows and black coloration running along their body and intense yellow coloration on their finnage, with the male displaying more coloration than the female as can be seen in the attached pictures.
Unlike the more common Poeciliid livebearers where the male impregnates the females with a gonopodium the goodeids have a more primitive development. The anal fin of the male poeciliids is fully developed into the gonopodium, which delivers the sperm to the females. In the goodeids the first two rays of the anal fin appear to be notched out of the fin and function as a primitive means to deliver the sperm to the females. Another difference between poeciliids and the goodeids is that in most of the goodeids there is a connection between mother and fry somewhat like a placenta that delivers nutrients to the fry, making them more comparable to mammals. A female poeciliid’s care for her fry on the other hand is almost comparable to a female mouthbrooding cichlid in that she provides protection to the developing embryos but all of the nutrients required for life come from the contents of the egg with no outside supplement. Poeciliids practice an internal fertilization and internal egg development. Another difference is that female poeciliids can store sperm for several months’ worth of fry while goodeids cannot. Thus a female goodeid needs to be re-impregnated after every batch of fry is delivered while a female poeciliid may have 5-6 batches of fry resulting from one male's fertilization.
A pair of Ilyodon furcidens and three fry were obtained from Mark Murtaugh and the pair was placed in a separate tank from the three fry. As with most livebearers a tank with clean moderately hard water in the mid to upper 70's usually satisfies their needs. Floating plants gives them someplace to hide and seems to make them calmer when they are swimming around the tank. As the young matured they turned out to be a male and two females. The female of the pair was thin and looked as if she had just had a batch of fry when I received her. She had their first batch of fry about seven weeks after receiving them, and a second batch six weeks later. The fry are large as are most goodeids although the Ilyodon had more fry than most other goodeids that I have kept so far. There were over 30 fry in the first batch. The fry are not very mobile for the first couple of days but do take freshly hatched baby brine shrimp and small pieces of flake food. After a few days they become much more active and grow rapidly. The parents ignore the fry and thus a community tank of them is quite easily achieved. |
