Optimum temperature and transportation density for tilapia ( Oreochrom/s niloticus) Broodstock in the semi-arid zone of Nigeria

Abstract

Oreochromis niloticus broodstock of mean weight 32.3g were cropped in the morning hours with dragnet from a 1 ha reservoir and transported in a circular tank to the Hatchery complex of the National Institute for Freshwater Fisheries Research where they were stocked into 4m x 3m indoor concrete tanks filled with clean water and aeration at a density of 4 fish/m2. They were acclimated for 5 days and then packaged into 60 litre capacity nylon bags at the following stocking density: 60, 80, 100, 120, 1 40 fish/60 lit bag. Each stocking density had bags with ice blocks and bags without ice blocks in triplicate. The nylon bags were oxygenated, loaded into quick fitting plastic bowls and transported in a bus from New Bussa to Warra, Kebbi State, a journey of 3 hours. The trip was repeated !our times. Percentage survival in bags with ice block were 1 00% for stocking density 60, SO, 100 flsh/60 lit bag, 95. 1 % for 1 20 fish/60 lit bag and S4.7% for 1 40 fish/60 lit bag (mean temperature 23.5°C). Mortalities were recorded in all the bags without ice block but the highest survival was in the bag with stocking density 60 fish/60 lit bag (mean temperature 29.2°C).

Keywords: O. niloticus, nylon bags, stocking density, temperature, survival.