Oscura heterospila

Oscura heterospila (previously assigned to various genera including Cichlasoma and Mayaheros) is a distinctive cichlid from the Yucatan Peninsula's coastal drainages, where it regularly encounters brackish conditions in estuarine environments. This halotolerance makes it one of the more ecologically specialized Central American cichlids. Adults display an olive body with variable spotting and a prominent dark caudal peduncle blotch.

In the aquarium, this tolerance for slightly elevated salinity can be used as a health management strategy — maintaining the tank at 1–3 ppt salt reduces susceptibility to several common cichlid pathogens. The species is otherwise straightforward in its care requirements and represents an interesting choice for hobbyists with hard or brackish-influenced tap water.

O. heterospila is a moderately aggressive medium cichlid that is suitable for mixed CA cichlid setups with robust tankmates. It spawns readily in captivity and both parents are attentive to the brood.

Water: 24–30°C, pH 7.0–8.5, GH 12–25, KH 6–15; tolerates 1–5 ppt salt; hard water beneficial. Tank: 250 L minimum; sand, rocks, minimal planting; can use slightly brackish conditions. Feeding: Omnivore — cichlid pellets, frozen foods, and green supplements; adaptable feeder. Breeding: Open substrate spawner; biparental care; moderate territorial defense. Compatibility: Robust CA cichlids of similar size; hard-water tolerant fish as tankmates.