Cyprinodontidae or egg laying tooth carp. A rather large group of fish. Killifish appear everywhere in the world except antartica and australia, yup, we have some here in the dfw area even. Killies come in a wide variety of shapes, sizes, and colors. In the wild, some lay thier eggs in plants while others prefer to burry the eggs in the substrate. Killifish lay one egg at a time rather than hundreds like cichlids. They also do not parent the young. Once the egg is layed, they are on thier own. Relying on tough, large fry rather than mass swarms to continue the line.

Killifish can be broken down into several groups, but we will go with two Annual, and non-annual. Annuals live for around, yep a year. Their natural habitat is most likely a puddle that dries up every year. So here we have these little guys swimming around in this muddy little puddle. Laying their eggs in the mud. Then the puddle dries up, fish die off, and it's like this little word has come to an end. Then the rainy season comes and wow, fish start hatching from the eggs left behind in the mud. With this kind of life cycle, it is entirely possible for a species to have a range the size of your living room. That's it, no where else in the world, but that puddle. Kinda cool if ya ask me.

Then we have non-annuals. Yes, they live longer than a year. Most of your non-annuals like to lay their eggs in plants and such, although some prefer soil, and yet others don't care and will use either or both. In this group is where we run into some of the "different" habits. The Rivulus, here is a strange bunch. They like to go for "walks" in the leaf litter. I have found them wondering around in my fish room floor a couple of times. The Kryptolebias marmoratus, talk about strange, you only need the one female. That's right, a self fertilizing hermaphrodite.

There are hundreds of species of killifish. All of them with their own interesting characteristics. The more you study up on these guys, the more interesting they become.