Tilapia Growout Time

Tilapia grow-out time vs water temperature

Nile tilapia (Oreochromis niloticus) is the freshwater fish Brazil farms more than any other, and how long grow-out takes depends heavily on water temperature. Hold the water near the sweet spot of 28°C and fingerlings hit a harvest weight of 800 g to 1 kg in 6-8 months. A rough way to estimate it is months = base_months × (1 + 0.06 × (28 − T)), so every 1°C you lose tacks on something like 5-7% to the cycle. Drop below 22°C and growth all but stops; push past 32°C and the fish run into thermal stress along with a weakened immune response.

Commercial operations stock all-male, sex-reversed fingerlings (treated with 17α-methyltestosterone during the yolk-sac phase). The reason is twofold: males put on weight 30-40% faster than females, and an all-male batch won't start breeding inside the ponds. In the southern states (Paraná, Santa Catarina) pond temperatures fall to 15-18°C over winter, which rules out stocking new cycles then. Most of the country's tilapia comes from Paraná, São Paulo and Goiás, feeding the domestic market and exports to the US.

Applications

Lining up stocking dates with the seasons when you plan the year's production. Scheduling harvest for processors and for direct sales. Projecting the feed budget, since cold cycles burn more feed per kg. And weighing net cages, which track lake temperatures, against heated tank systems.

FAQ

How long does tilapia take to grow at 28°C? Roughly 6-8 months to go from a 1 g fingerling to an 800 g-1 kg harvest weight, provided the feeding is managed well.

What if temperature drops to 24°C? Figure on the cycle stretching about 20-25%, so 7-10 months to reach the same weight. Feed conversion gets worse too.

Can I farm tilapia year-round in southern Brazil? Not in earthen ponds, where winter brings growth to a stop. For continuous production you'll need heated raceways or RAS (recirculating aquaculture systems).