American Flagfish

Native to Florida and the Yucatan Peninsula, Jordanella floridae is a small killifish with a surprisingly big personality. Males are the showstoppers, wearing a pattern of red horizontal stripes over an iridescent blue-green body that genuinely does call to mind the American flag. Females are more subdued, brownish with a dark spot near the dorsal fin, but still attractive in their own right. They top out around 6.4 cm, so they're not large fish, but they carry themselves with the confidence of something twice the size.

One of the most practical things about flagfish is their genuine appetite for filamentous algae, particularly hair algae and thread algae, which most fish ignore entirely. They'll graze on it methodically and can make a real dent in a tank that's been struggling with an outbreak. However, they're omnivores and need a varied diet beyond algae alone. Quality flake, occasional frozen foods like bloodworm or brine shrimp, and blanched vegetables all belong in their rotation.

Water parameters are forgiving across a wide range. They handle everything from slightly acidic to moderately alkaline conditions, and their cold tolerance is genuinely unusual for a tropical community fish. Unheated tanks in temperate climates are viable if temperatures don't dip below 18C, which opens them up for pairing with other coolwater species.

Tanks should be well-planted with open swimming space in the center. Dense vegetation is more than decoration here, it's functional cover that reduces aggression and gives females somewhere to escape. A tight-fitting lid is worth mentioning because like most killifish relatives, they can and will jump when startled.