Tilapia are a hardy, aggressive freshwater fish originally native to Africa that reproduce quickly and eat a grain-based vegetarian diet. This fish grows fast and can reach a size for harvesting within eight to 10 months. Tilapia is a white fish with a bland flavor that makes it a good substitute for other white fish, including snapper, grouper, flounder, and rockfish. Tilapia is available year-round fresh and frozen, whole and in fillets, and frozen value-added fillets. According to some buyers, the quality of frozen tilapia fillets can vary so it is recommended to stay with a good brand to ensure consistency. fillets are available in several graded sizes: 3-5 oz, 5-7 oz, and 7-9 oz, with 5-7 oz being the most common grade.
The nature of the fish makes it taste like the water where it was raised, so the best quality has the cleanest taste. Most frozen fillet producers in Taiwan and China treat the fish with carbon monoxide to give the bloodine a red color; these fillets are frequently marketed as sashimi-quality snapper even though they aren’t and do not have the same quality. To make sure their tilapia crop is male, some farmers use a hormone called methyl testosterone that, although deemed safe by the U.S. Food and Drug Administration, has caused some buyers to seek non-treated fish.
In the United States, tilapia farms tends to be held to higher environmental requirements than farms in other countries, according to the New England Aquarium. However, the aquarium says that tilapia farms in Latin America generally have good environmental practices. The Chinese government put guidelines in place in 1990 to prevent alien fish species from being introduced to native populations.
American tilapia systems tend to release small amounts of effluent.
In Asia and Latin America where tilapia farming is intensive, farming can cause local waterways to have higher nitrogen and phosphorous levels, leading to heavier algae growth. Some Mexican tilapia farming operations enhance the habitat by using effluent to irrigate trees, reforesting watershed areas.
Tilapia are farmed in earthen ponds, floating cages, or in indoor recirculating tanks. In the United States, tilapia are farmed in closed tank systems, which reduces the likelihood of escapes. Most tilapia come from farms in Southeast Asia and Latin America. Asian farmers usually treat effluent before discharging it, however poorer rural areas do not always treat it. In Latin America, several independent companies have created best practices for tilapia farming, but the effectiveness of these measures is unclear. Tilapia’s hardy nature reduces the need for pesticides, antibiotics, drugs and other added chemicals. However, the practice in Mexico of raising the fish in drainage water is potentially hazardous due to leaching chemicals. In the United States, the Environmental Protection Agency requires fish farmers to hold discharge elimination permits. American tilapia systems tend to release small amounts of effluent.
Tilapia are vegetarian and primarily fed a grain-based diet. However, some farmers use feed that contains low amounts of fish meal and oil. In Latin America, farmers use feed that contains as much as 8% fishmeal, although it’s usually 5% or less. In Asia, many farmers add fertilizers to the water, encouraging phytoplankton and zooplankton to grow so that less feed is required.
Escapes and Introduced Species
Tilapia are disease-resistant and able to survive in poor water, making the likelihood that escapees will survive very high. Since tilapia are non-native to the United States and threaten native freshwater fish, U.S. farms minimize the risk by employing recirculating systems. Open pond tilapia farming is prohibited in the United States. In Asia, tilapia often escape ponds when they become flooded from rainfall, but their impact on native populations is not fully known. Asian farmers also raise the fish in cages and tanks. Tilapia escapees from tilapia ponds in Central and South America have been linked to the decline of native freshwater fish species. In Mexico, farmed tilapias have been known to spread parasites to native fish.