The majority of tilapia production is produced by small family businesses that operate one or two ponds or cages. Only a few bigger companies engage in large-scale tilapia production operating integrated supply chains. Most of the operators focus on producing smaller sized tilapia of 200 – 300 grams, with some operators producing even smaller sizes (100 – 150 grams), all for the domestic market.
Farmers acquire fry (measuring 1 to 2 cm) from one of the smaller hatcheries that are based throughout the country. To ensure a high survival during the sensitive juvenile stage these fry are first grown in small hapa nets in nursery ponds (max. 2,000m2). During the nursery stage the fish receive daily care. High protein feeds are used to boost their growth. After around 30 days the fish are large and strong enough to be transferred to the bigger grow-out ponds (0.5 – 4 hectare) at a density of 50,000 – 70,000 fingerlings per hectare. Ponds are typically made by raising earthen walls in low-laying coastal areas after which the soil and walls are pounded to improve the structure and to it watertight. Ponds for tilapia culture have an average depth of 1 meter.
Weekly care consists of promoting algae growth in the ponds by applying chemical fertilizers and using pellet feeds or rice meal three to four times a week as main feed. If needed, partial water exchanges are done using pumps (in freshwater habitats) or tidal currents (in brackish water areas). In most cases no active aeration systems are used. Depending on the targeted harvesting size and the amount of feed used, the fish remain in the grow-out ponds for around 5 to 6 months. Typically fish are harvested at 250 gram but some farmers grow the fish to larger sizes.
Cage farmers use a similar pond based system for the nursery stage after which the fingerlings are transferred to floating cages at a density of 200 – 300 fingerlings per m3. Since natural algae are not available at sufficient densities in marine waters, more feed is needed during production resulting in a higher FCR. The duration of the grow-out period and harvesting sizes are similar to those in intensive pond farming systems. In both situations, hatchery production, stocking and harvesting take place all year round.