Effects of broodstock sex pairing ratios and rest periods of the nile tilapia Oreochromis niloticus on fry production

Abstract

 This study evaluated the effects of varying male to female brood stock pairing ratios of 1:1, 1:2 and 1:3 with resting intervals of 0, 3 and 7 days on fry production of the Nile tilapia at the Aquaculture Demonstration Centre (ADC), Ashaiman, Ghana. Nine (9) treatments were arranged according to a 3 x 3 factorial design with three replicates giving a total of 27 spawning hapas (1 m³). Male and female brooders of mean body weight (229 ± 5.43 g and 171.6 ± 21.7 g respectively) were paired at the different sex ratios. Water temperature and DO were taken daily whiles pH, salinity and ammonia were measured weekly. All the water quality parameters were within suitable range for Nile tilapia fry production. The total mean fry output for the sex pairing ratios (1:1, 1:2, 1:3) were 716 ± 344, 973 ± 325 and 723 ± 577 respectively. The total fry output for 0, 3 and 7 days of resting were 1503 ± 868, 2030 ± 637 and 3051 ± 1054 respectively with an observed 35% (3 days rest) and 103% (7 days rest) fry production increment over the 0-resting treatment. With respect to the combined effect of varying sex ratios and resting periods, the highest mean fry production (701 ± 405) was attained under the 7 days resting period at a pairing ratio of 1:2. The high reproductive performance of broodstock pairing ratio 1:2 and resting period of 7 days under this study confirms its efficient as a broodstock management technique for an increased Nile tilapia fry production.