Central and southern North America boast a number of native killifish species, some of them as interesting as any found in Africa or South America. One rarely seen in the hobby is Adinia xenica, the Diamond Killifish.
A peaceful, active and beautiful species, A. xenica is native to the salt and brackish water tidal swamps and mangroves of the southern U.S. from Florida to Texas. It appears to adapt well to various salinity levels, although it will only thrive and breed in brackish or salt water. It will survive in fresh water, but long term maintenance in fresh water presents problems; the fish may develop enlarged thyroids (hyperplasia).
The male is basically dark gray with a large number of unequally sized vertical silver bars marking the sides. The unpaired fins are dark gray to nearly black, with silver spots and stripes. The dorsal usually sports a white border, and the anal fin may have a yellow tint. Females are similarand the unpaired fins show gray mottling.
Neal Foster reports that he has kept A. xenica in one-sixth seawater. Mike Wilson has maintained his in salt water with a specific gravity of 1.012, along with Floridicthys carpio. He suggests use of a power filter, since the fish revels in water currents. Mike and Jaap DeGreef have collected this species in coastal mangrove areas with numerous inlets that experienced strong tidal influences. “Interestingly, we’ve never been able to find A. xenica in the area at low tide. When tidal influence is bringing in the water, there are small groups or pairs all around. As long as we go to collect on the incoming tide, we can be assured of the collection of some specimens.”
Mike says that the species is easy to feed and breed, but that they seem to do best in groups for long term maintenance, and in pairs for breeding. “A group of 6 to 10 adults in a 20 long is an attractive sight, with very little aggressive behavior apparent.” Newly hatched brine shrimp seems to be the food of choice, but other foods (including dry flakes) are readily accepted.
The eggs are placed in mops, on corks, in gravel, in filters, in rock crevices. “If you can’t find eggs where you expect them,” Mike says, “just keep looking.”
Incubation is fairly short, with bad eggs occurring only infrequently. The eggs are large and although few are produced at any one time, the females tend to produce a few eggs each day over a long period.
The fry grow rapidly, with sexual differentiation occuring at about three months of age.
— G.C.K.A. Newsletter, June 1997