Tilapia

Nile tilapia, Mozambique tilapia, Blue tilapia, St. Peter’s fish

Tilapia is the common name for many cichlid species within three genera: Oreochromis, Sarotherodon, and Tilapia. The species of greatest importance to aquaculture are the Nile tilapia (Oreochromis niloticus), Mozambique tilapia (O. mossambicus), and Blue tilapia (O. aureus) and their hybrids. According to the United Nations Food and Agriculture Organization in 2003, 82% of cultured tilapia are Nile tilapia.
Tilapia are easily cultured because they are omnivorous and can adapt their eating habits to available food. In addition, they can tolerate low oxygen levels and a wide range of salinities and can be farmed within a wide range of densities. They also have high reproductive capacity
and readily establish self-reproducing populations. Tilapia occur mainly in freshwater but also in brackish water and seawater in tropical and subtropical climates. They occupy a wide variety of habitats like rivers, lakes, sewage canals and irrigation channels. Tilapia feed mainly on phytoplankton or benthic algae but readily accept compound feed (with plant or animal protein).
Males grow faster than females, mainly because females begin reproducing early and thus divert their energy to reproduction instead of growth. There are several methods used to avoid loss of marketable biomass through excess
reproduction. Farming in cages does not allow females to pick up eggs for oral incubation,which eliminates reproduction. Culture populations that are exclusively male are also often desirable to control reproduction and maximize biomass production.

Various estimates of the amount of fish protein in, to fish protein out for farmed Tilapia are less than 1:1 in nearly all cases. This indicates that tilapia culture results in a net gain of edible fish protein. There is therefore a “low” conservation concern regarding the current use of marine resources in most culture practices. However, some caution is warranted, especially in China where over-formulation of feeds may result in the overconsumption of wild fish for optimal tilapia growth.

Tilapias readily invade and naturally reproduce in warm waters where they are introduced. They are currently established throughout much of the world, but experts strongly suggest that nonnative tilapia should not be farmed in new or pristine areas because escapes are inevitable with serious negative results. Non-native tilapia populations have been found to compete with supplant or “devastate” wild cichlids and other native species. Eradication efforts in Florida have failed. Continued escapes are expected, particularly in open systems (nets, cages, and flowthrough raceways), meriting high concern. However, even relatively closed systems (ponds,recirculating tanks), unless enclosed in a structure, are still compromised by storm events and merit continued concern. Overall this criterion is considered a “moderate” conservation concern.

Though there are few reports of disease and parasite transfer from tilapia introductions, stocked tilapia can become infected from wild stocks prompting a “moderate” ranking for tilapia culture in nets, cages and raceways for unenclosed ponds and tanks. Whereas, organically certified tilapia farms are required to focus on preventing outbreaks by maintaining natural environments and behaviours, and infections are treated promptly Organic, enclosed ponds and tanks receive a “low” rating for conservation concern.

U.S. EPA regulations are comprehensive for effluent treatment for US tilapia aquaculture farms meriting. Effluent is used for agriculture rather than being released into natural water bodies. Risk for organic product internationally may be low as well, but lack of demonstrated effectiveness warrants caution and a rating of “moderate” risk for organic tilapia. The risk of pollution is likewise moderate for semi-intense and intensive operations that are closed to the environment (ponds, tanks), but higher for semi-intense and intensively stocked, open systems (nets, pens, raceways). There is also a moderate but growing concern for pollution in China and Central America where rapid development of intensive cage culture continues prompting a “high” conservation concern ranking.

The management in China appears to be “ineffective”. The US has recently implemented national effluent limitation guidelines and Best Management Practise plans for aquaculture, and the US management regime is effectively enforced; thus US management, as well as organic management, is deemed “effective”. Most other countries appear to have underdeveloped management plans that merit “moderate” levels of concern.

Where was this tilapia farmed?

Contaminant levels do not warrant a consumption advisory.