Breeding the Shortfin Bichir (Polypterus palmas)

Polypterus palmas is a smaller West African bichir; like its relatives it spawns via anal-fin fertilisation in the rains and is rarely bred in home aquaria.

Overview

The Shortfin Bichir (Polypterus palmas) is a medium West African polypterid reaching about 35 cm SL. It is a freshwater, bottom-dwelling, facultative air-breather from coastal rivers of the Gulf of Guinea, from Guinea-Bissau to Liberia and the upper Casamance and Cavally rivers, and is listed as Least Concern by the IUCN (FishBase). As with all bichirs, captive breeding is rare (Wikipedia).

Sexing

The reliable external cue across Polypterus is the anal fin, which is noticeably broader and thicker in mature males because it forms a cup used to direct and fertilise eggs (genus account, Wikipedia).

Conditioning

Reproduction in bichirs is tied to the rainy season and to shifts in temperature and water chemistry. Adults are conditioned on meaty foods, then exposed to simulated seasonal change. The smaller adult size of P. palmas makes housing breeders more feasible than for the giant species, though success remains uncommon.

Spawning Behavior & Trigger

A ripe male cups his anal fin beneath the female to catch and fertilise eggs as they are released (genus account, Wikipedia). The recognised trigger is imitation of the rains: generous water changes with soft, cool water that lower conductivity, followed by a rise in temperature.

Egg & Fry Care

Eggs are slightly adhesive and adhere to plants. Polypterid larvae hatch bearing branched external gills like those of salamander larvae, which regress as the fry grow (genus account, Wikipedia). Bichirs do not generally guard their spawn, so eggs and fry should be separated from adults.

Common Challenges

Even at this smaller size, reliably forming pairs, recreating the seasonal flood cue and protecting eggs and larvae from predation are the main hurdles, and documented home spawnings remain scarce.