Though uncommon in shops, killifish have been in the hobby longer than almost any fish one could think of. Sailors brought back killies from distant ports as early as the mid 19th century, trading the glittering little fish for necessities, with the first international killies kept in the US arriving just after the first world war. Most killies available are native to West Africa and the United States, with a handful from Southeast Asia and South America.

And glittering they are. Some are so brilliant to put marine fish to shame. And though they range in size from a bit over an inch to nearly six inches, killies, given proper environs and foods, can be easily kept. But the potential keeper must keep the killie tank tightly covered, since many of these fish jump, some of the larger species over 12 inches above the water level.

In this primer we'll cover several species and their care. There are but a few tenets before one delves into killie keeping; though a few are common, finding a quality source for them can be a challenge, most will only take live foods initially, and many must be kept in a tank by themselves.

But, killie keeping is a deeply rewarding experience, as generations of killies can be raised by a keeper. And there's also a thriving national organization: The American Killifish Association, in which members can trade fish, eggs, the latter even internationally. Much knowledge can be gained in the art of killie keeping, and the annual AKA national convention is not to be missed.

There are two types of killies available - annuals and perennials. Annuals evolved in pools that dry up in the dry season, thus they grow fast, lay their drought resistant eggs, and the adults die as the pools evaporate. Though annuals don't necessarily live just a year, a keeper is both fortunate and skilled to keep them past two years. Most aren't really tropical, so 72 to 76 would be the proper temps.

Perennials can live quite some time, many easily five years, some of the larger species as many as eight or nine. In this list we'll start with the perennials.


Native to the southeast corner of the US is the Florida Flag Fish; Jordanella floridae.

Male Flag Fish reach 2.5 inches and possess the majority of the colors, like nearly all killifish do. Native to Floridian swamps, males sport a metallic, silvery body, moving toward a blueish top. Red stripes along the fish with the blue give it its common name. The unpaired fins are greenish to blue green and marked with red striping. She is a little smaller, her silver is greenish, stripes are dark and unpaired fins sport an orange cast near their bases. Her dorsal has a dark spot below it, and more dark spots are usually scattered about her. Both sexes can change colors at will, so she can be barred occasionally with varying levels of green and silver, and he can look uncannily like an American flag when at his best when morning sun hits the tank,

In feeding, Flag Fish MUST have real, green algae in their diet, and they'll make short work of any algae that may crop up. Given the algae, Flag Fish are quite hardy, and will happily take live, and eventually even frozen, foods. It isn't uncommon for Florida Flag fish to live five years and more. This is one fish that should be moved to a species tank, as the male is too combative toward his mate and tankmates when spawning, for the community aquarium. Though Flag Fish are killies, or more properly, American pupfish, the males behave almost Cichlid-like fanning and vigorously defending the eggs. Younger specimens that are below spawning age should be kept in a group, and do well in a peaceful community setup.

Flag Fish can and should be kept in a well planted tank, though they may nibble the plants, but daily feedings of soft green algae cultured on stones usually prevents that. They eschew the bright light of well planted aquaria, so floating plants over the main swimming area will keep your Flag Fish group continually visible. Flag Fish prefer their water slightly alkaline; pH 7.2 is best, and moderately soft, with temps between 68 and 75. You'll want to keep your tank very well planted, because once they mature, Flag Fish always breed, usually at the base of a plant. He drives the female hard, and he guards the eggs and fry with vigor. The plants are necessary so she can get out of his line of sight, and one night she should be removed to another container to escape his attentions.

The eggs hatch in a week at 75 degrees, longer at warmer temps. He's an attentive father, and keeps his flock close by at all times. The youngsters are easily raised, taking live baby brine shrimp as soon as they are free swimming, transitioning to larger foods and algae as they grow. If you swipe the fry to raise them yourself one evening, he'll promptly look for another female and spawn again.

Florida Flag Fish are among the easiest killies to find, and better fish stores usually have them on their lists.