Family Ciprinodontidae (Killifish) --- Introduction
It is a large family that contains more than 700 described species. Many species vary in the color as well as pattern, and also numerous subspecies and local forms (populations) are known. Killifishes are closely related to family Poecilidae (Livebearers). They can be found in every continent except Australia. In Africa and South America they are distributed across the continent except in the southern part. In Europe, North America and Asia they inhabit temperate zones.
The family Ciprinodontidae includes generally small-sized fish (Fish from the family… are generally small-sized), although some species can reach 30 cm. Most killies have pike like body and flattened top of the head. Males are larger, having more intense coloration and longer fins. Many species particularly those that belong to the genus Aphyosemion and Nothobranchius are remarkably colored.
From some reason unknown to me, killies are rarely available in pet shops. The best way to obtain these beautiful fish is to join some Killie club. Main objectives of these organizations are conservation, maintenance, propagation and distribution of Killifish species. Some national associations like American Killifish Association and Deutschen Killifisch Gemeinschaft have quite many members. Here in Serbia (Yugoslavia) group of enthusiasts are trying to establish a Killie Club of Serbia.
Killies have one very interesting feature that makes the existence of the Killie clubs as well as contacts between breeders more important. Their eggs can be sent across the world in the letter!!!
How is that possible?
Waters where they live are in tropical and temperate zones. Partial or complete evaporation of these waters, during the dry periods, will be fatal for species that haven't developed some way to survive. Through the evolution the Killifish have developed a few interesting qualities. First is that their eggs can survive without water in shorter or longer period during development. It is necessary that substrate where they are deposited have some amount of moisture. The second quality is a special dormant period during their development, so called diapause. That enables the eggs to wait for proper hatching conditions. After first rain most of eggs hatch, but some eggs remain. As a matter of fact some Killie eggs can develop after a year or more. They stay as reserve in case of bad conditions. It is the way for survival of the species.
According to the development of the eggs Killies are divided in 3 categories:
1) Non-annual species
Killifishes that inhabit permanent waters, where the water does not dry up during whole year. Their eggs have continuous development without diapause.
2) Annual species
Killifishes that inhabit waters that dry up periodically. Their eggs go through diapause.
3) Semi-annual species
Killifishes that inhabit waters that dry up more or less for a short time. Their eggs can develop in both manner, annual or non-annual.
Two hundred million years ago there were only 2 continents. One of approvals on that theory is existence of related species on different continents, which means that killifishes ancestors were already developed when continents started to detach.
TWO HUNDRED MILLION YEARS!!!
How many beautiful killifish species had developed and disappeared since than, and how many beautiful killifish we fail to keep?
That is the truth, but do not be disappointed, we still have enough species to keep.
MORE THAN 700!!!
So, let’s keep.