Cyprinodontidae Killies

The Cyprinodonts (meaning "toothcarps") flourish in virtually all the world's tropical inland waters (Australia excepted), with over 500 species in all. They have teeth, and their mouths are oriented upwards to seize prey on or near the surface; some species can even leap out of the water. They dwell in calm, stagnant, and shallow waters, sometimes mere puddles, which are liable to dry up. In this case, the adults perish, but their eggs survive: see Reproduction, page 60. They are small in size, rarely exceeding 8 cm. vividly colored, and are prized by some enthusiasts for their remarkable breeding habits. There is much confusion between species, especially since coloration varies between geographically diverse populations. Only a few are regularly handled by dealers; most are exchanged between killie-fanciers, killies or killifish being the popular name for these species.

How killies reproduce

Those killies whose habitat never dries out deposit sticky eggs which take several weeks to incubate. Those dwelling in areas prone to periodic drought have developed a special method to ensure the survival of their species. The eggs spawned in the mud undergo a period of dormancy in their development (the diapause) for as long as the drought lasts. At the first rains, development resumes and the eggs hatch. Thus their incubation period may last from 3-6 months, and they have no need to be adhesive. You can tell thathatching is imminent when you can see the eyes of the embryos through the eggs.

Caring for killies in the aquarium

Ideally, you should provide a special small tank (10-15 liters) for each species. It is also possible to put males of different species in one tank; this will provide a colorful spectacle, but do not put females together, as many of them are so much alike that you will have trouble telling whichspeciesiswhich, Conditions must be soft and acidic, so you will need to use peat filtration;

sometimes, if you put a layer of peat on the bottom of the tank, the fish will use it to lay their eggs on. The maximum temperature should be 24°C. Killifish are very fond of small, live prey, but will also take dried foods.

Preserving and transporting eggs

Hobbyists who live a long way from one another can exchange killie eggs through the mail. The incubation period is sufficiently long to enable them to be transported, as long as they are kept in damp, cool conditions. The seasonal species can withstand much drier conditions than continuous breeders: lower temperatures serve to prolong the diapause. Make sure that the boxes or plastic bags used for transport are completely airtight. To start the eggs hatching,return them to water.

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