- 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.