Is farmed fish bad for you?

Sweeping claims about toxins contained in farmed fish, which are supposedly dangerous to human health, are unsubstantiated and false.

Is-farmed-fish-bad-for-you
Tilapia sushi is an attractive food product produced from red tilapia.
Photo: Nicholas James

A series of alarming publications concerning the safety of tilapia consumption has recently surfaced on the Internet. Some of these supposedly ‘healthy nutrition’ sites are spreading unfounded rumours based on half-truths and disinformation. Tilapia are claimed to be “more dangerous for your health than some of the more notorious meats such as pork and beef”.

These accusations are directed at the entire industry and do not distinguish between different production systems or locations.

All farmed fish are not equal
In China, tilapia is produced on an industrial scale. Large quantities are exported, mainly to the US but also to Africa. Fish farmed in polluted districts close to industry in China (or anywhere else) are likely to be polluted themselves, and may indeed contain traces of pesticides, dioxins, carcinogens and other substances detrimental to human health.

However, to declare that all farmed fish is equally toxic is false and downright malicious.

It equates to suggesting that all agricultural produce is toxic, regardless of geographic origin or method of production.
To quote from this nonsense: “Farmed fish has ten times the normal quantities of carcinogenic agents compared [with] wild fish. Farmed fish also contains more pesticides, usually used for treating the fish for infections.

These pesticides often remain in their bodies after harvesting. Another issue associated with the farm-raised fish is the high level of dioxin in them. This substance is lethal, and when you take it into your system, it may remain there for up to a decade. Farmed fish contains 11 times more dioxin than wild fish.”

Yes, some Chinese tilapia may be unhealthy, but most is probably not – just like any other agricultural product.
Such generalisations call into question the motives of the writer, and such sweeping and unsubstantiated statements give the Green Movement a bad name.

Twisting the truth
It was also claimed that farmed tilapia “are fed chicken poop”. In Africa, tilapia is reared either in cages in lakes or in ponds, often fertilised with animal manure. The erroneous assumption is that the fish eat the chicken waste. This is incorrect.

The manure breaks down in the water, and causes a bloom of zooplankton and phytoplankton – natural feeds on which the fish thrive. Any water that is green in colour contains an abundance of these microscopic organisms, amongst which are various algae, crustaceans and aquatic insects. A fish fed on these will be healthy and nutritious to eat, just like a fish in the wild.

African fish production
Fish reared at higher densities in closed recirculating systems are fed pelletised diets that are maize- or soya-based. Zambia is a major producer of non-GM maize and soya, much of which is exported to South Africa.

Feeds made from these crops are entirely safe for both the fish and the consumer. No pesticides are used in such culture systems; in fact, all such toxic substances are highly toxic to fish. If water sources are clean of industrial effluents, then no dioxins or carcinogens can be present. Also, I do not know of any African tilapia producer who uses growth hormones.

Tilapia reared under such ideal conditions can certainly be termed ’organic’ and are amongst the healthiest foods to eat.

Nicholas James is an ichthyologist and hatchery owner. 

This article was originally published on 18 March 2016 in Farmer’s Weekly.