Effects of Incision Variation Length on Heterobranchus bidorsalis Male Spawners to Extract Milt for Induced Breeding

Matured African catfish (Heterobranchus bidorsalis), size ranging from 1.40-2.00 kg average total body weight (TBW) and mean length 44.50 cm were procured from a private fish farm and transported in perforated 50 litre water holding capacity jerry can to the hatchery and maintained for 2 weeks. They were fed with 40% crude protein commercial diet with good water quality management before being used for breeding. Incision at variation length 2.50, 3.40 and 4.00 cm were made on the abdominal region (gonad position) of the male spawners after anaesthetic treatment using sterilized surgical instrument to extract milt to fertilize egg. The incised position was sutured using simple interrupted suture pattern with catgut chromic 2/0 stitch. The spent spawners after operation survived on gradual healing and recuperation within 14 days post- surgery. Fecundity, volume of milt extracted, percentage fertility and hatching differed significantly (P<0.05) among treatments. Treatment 3 (3.40 cm) was the most effective incision length that gave best results in term of percentage hatching (92.04a), weight gain (28.37), specific growth rate (2.36) and percentage survival (68.77±4.224a) of the bred hatchlings as compared to other treatments. The male spawners of H. bidorsalis could be incised (cut) on abdominal region (gonad position) at length of 3.40 cm to effectively extract milt to fertilize egg without adverse effect on the fish to enhance fingerling production.