Influence of temperature on egg hatching, growth and survival of larvae of Heterobranchus longifilis Val. 1840 (Teleostei: Clariidae)

Eggs of Heterobranchus longifilis Val. 1840 were artificially fertilized and incubated at a range of temperatures (20, 23, 25, 27, 29 and 32°C). The time from fertilization to hatching decreased with increasing temperature. No eggs survived to hatch at 20 and 32°C incubation temperatures, while at 23 and 29°C hatching was only minimal. Optimum hatching was obtained at 25 and 27°C, which corresponds to the ambient temperature range during the breeding season. Larvae of H. longifilis were reared for 11 days post-hatching at 20, 25, 27, 29 and 32°C. Growth increased with temperature (P < 0.05), whereas survival depicted an inverse relationship. Growth was minimal at 20°C and larvae rarely survived to the end of the experiment. Optimum temperature for the primary nursing of H. longifilis larvae was within the 25–27°C temperature range.