Palon Killifish

The Palon killifish is a small annual killifish belonging to the genus Nothobranchius, a group of short-lived fish native to seasonal pools across East Africa, with this species associated with coastal Kenya and Tanzania. Like its relatives, it belongs to the family Nothobranchiidae within the order Cyprinodontiformes and is adapted to a boom-and-bust life cycle tied to temporary rain pools. Males display bold coppery-orange and blue coloration typical of the genus, while females remain plain. The species is best known through the aquarium and killifish-breeding hobby, where East African Nothobranchius species are prized for their intense, short-lived breeding coloration.

Palon killifish are small, rarely exceeding 5 cm.

• Body: slender and slightly compressed, typical of surface-oriented annual killifish
• Male coloration: coppery orange-red body with iridescent blue speckling concentrated on the head and upper flanks
• Tail: blue-gray with a narrow red submarginal band
• Female coloration: plain gray-olive with rounded, unpatterned fins
• Fins: dorsal and anal fins set well back toward the tail, largest and most colorful in mature males

As with other Nothobranchius, precise identification of color pattern often depends on knowing the collection locality, since closely related populations can look very similar and hybridize where their ranges overlap in the aquarium hobby.

This species occupies small, temporary freshwater pools that form during the rainy season in coastal lowland areas of East Africa, in the vicinity of Kenya and Tanzania. These pools are shallow, warm, and often muddy, drying out completely during the dry season and leaving the species with no permanent aquatic range. As with related Nothobranchius, the fish survives the dry months only as diapausing eggs buried in the substrate, hatching again once seasonal rains refill the pool. It shares this fragmented, boom-and-bust habitat pattern with numerous other Nothobranchius species scattered across East African coastal savanna.

Palon killifish grow and reproduce quickly to complete their life cycle before their seasonal pool dries out. Pairs spawn by diving into soft substrate to bury eggs, which enter diapause and can survive months without water. Adults are active surface and midwater feeders, taking mosquito larvae, small crustaceans, and other invertebrates throughout the day. Males compete for access to females and defend loose territories around preferred spawning substrate. Once the pool dries completely, the adult population dies, and the population persists solely as buried eggs until rain restores the habitat.