The fish were harvested from Mr. James Paddy of Osajai cluster in Teso North District.
The fingerlings of the monosex male tilapia were sourced from Wakhungu Fish Farm and stocked on the 2nd May 2012 in an earthen pond under semi- intensive culture system. The ponds were fertilized using manure, two weeks prior to stocking. The stocked fry fed on the phytoplanktons and zooplanktons for one month, and were thereafter introduced to peleted floating industrially manufactured feeds for 257 days. At the time of stocking, the average weight of the fry was about 3 g, whereas at the time of harvesting on 13th February 2013, the biggest fish was weighing 1.066 Kg, followed by 0.923 Kg and the average weight was 0.8 Kg.

Temperature tolerances

• Temperature is the most important variable affecting the growth of larvae and early juveniles.
• The optimal temperature for growth appears to be 30°C; however, temperatures in the range of 26-33°C are known to yield acceptable growth performance.
• At temperatures below this range, growth rates decrease but survival is still good. However, 28°C is the optimal temperature for both yolk sac absorption and maximum growth rate.
• High temperatures can encourage the growth of harmful bacteria and fungi, however.

Temperature tolerances

• Various strains of Nile tilapia differ with respect to their tolerance to cold, but growth is generally limited at temperatures below 16°C and most strains become severely stressed at 13°C.
• Death begins to occur at 12°C, with few fish surviving temperatures below 10°C for any period of time.
• Nile tilapia do not feed or grow at water temperatures below 15°C and do not spawn at temperatures below 20°C.
• The normal water temperature should be 20-30°C, preferably about 28°C, which is considered the ideal temperature for good health and growth. At higher temperatures their metabolic rate rises, leading, in extreme cases, to death.
• Gradual conditioning would allow tilapia to live within a range of 8-40°C.

Tolerance of low dissolved oxygen (DO) concentrations

• Tilapia are able to survive levels of dissolved oxygen (DO) below 2.3 mg/L as long as temperature and pH remain favorable.
• In fertilized ponds, a bloom of algae can reduce oxygen levels to as low as 0.3 mg/L with no fish mortality in tilapia.
• Larger fish are known to be less tolerant than fingerlings; this is due to metabolic demand.