Killifish, and a note on Livebearers
Killifishes, which are in the family Aplocheilidae and the familiar livebearers, in the Poeciliidae, are both members of the Cyprinodontiformes ("tooth-carps"), a group that also includes marine flying fishes and silversides. The order is circumtropical in distribution, in all the world's warm seas, and in freshwaters of Africa, India, Australia/New Guinea and in the Americas.
The Killifishes are tangled in a massive web of confused genera. Killi fanatics behave like Malawi cichlidiots and often skip the genus, just referring to their fish by its specific name: thus my first killis are "Gardneri." When true killi fanatics are alone with one another, they sometimes strip this specific name down to a three-letter designation; thus my killis would be "GAR." A more important distinction among the true killifish pros are the populations from which the strain in question was driginally drawn. By keeping populations distinct and identifiable in aquarium practice, the possibility of hybridising these endangered fishes out of existence is avoided. Females tend to look alike.
The life cycles of killifishes divide them into two broad categories: the truly "annual" South American fishes whose environments dry out, with eggs incubating in the damp mud to carry on the species, and the longer-lived, easier to care for African and Indian species. The killifishes are surely the most undervalued group of small freshwater fishes, except among the killi fanatics, who know! In spite of the glorious colors of the males, they can be shy or pugnacious with their own kind and don't often thrive in the average community aquarium. This means it's difficult for your LFS to carry them. But killifish eggs, packed in damp peat moss, travel through the mails almost as easily as daffodil bulbs. Most killifish are only available through members of the killifish associations or local branches.
Links. Richard J. Sexton's site Killi.NET, with a lively first-person slant to it, is a good place to start. The site offers a wide range of information and links to national killifish associations around the world.
The International Killifish Association maintains a comprehensive site with all the basic information. Articles from killi club newsletters are archived and links will guide you to all the web's killi-connections.
The British Killifish Association (BKA) maintains a site with articles, photos and species information, with breeding reports and a "members-only" section.
The American Killifish Association (AKA) site is another place to look for info and links. The site is oriented towards members of the AKA, with a "members-only" section.
The Killi-Data On-line site offers the most extensive ichthyological and historical information about all the egg-laying cyprinodonts. You need to register. The guest site has news, killi biotope information, services, etc. slanted toward aquarists.
The Killie Nutz site, redesigned as a wiki, offers a trove of news, lore, photos, and encyclopedic killi articles.
In Sweden, Alf and Anita keep a wide range of killifish; she's the head of the Skandinaviska Killi Sällskapet, and their apartment looks like this! It's about the closest I ever came to a pang of envy.
And you'd better scope Bill Shenefelt's site "Shene's Killies" for detailed descriptions of killi spawning techniques.
Livebearers. As a child I kept guppies, mollies, swordtails and platies, but I don't have any very personal addition to the many accounts of these fishes you can find all over the web.
Viviparous: the Livebearer Information Service offers you some advanced Brit livebearer fishkeeping, with information on some unusual species and live food culturing, in a slightly rough-edged format. Recommended.