Fishy Business: Hormones Used to Cause Sex Change in Tilapia

tilapia fillet

This article was recently published on

Drug Induced Fish: Hormones Cause Tilapia to Undergo Sex Change
Monday, April 06, 2009 by: Barbara Minton, Natural Health Editor

Has the fish on you dinner table gone through a drug induced sex change? If the fish is tilapia, the answer is probably yes. Tilapia is a delicious, mild flavored fish that has become very popular because of its low price. This low price is achieved by converting the young females to males through the use of the hormone drug 17alpha-methytestosterone. Raising an all male population allows fish farmers to produce bigger fish in a shorter time period with less feed. It also allows them to produce fattened profits. The only problem is that consumers have no idea the fish they are eating have undergone hormone-induced sex changes, and the long term consequences of such changes to health and environment are as yet unknown.

Almost all tilapia sold in the U.S. is hormone drug treated

. . .  The problem with these fish is their quick maturation at two to three months of age, and their ability to start breeding at a rate of once a month. These characteristics result in the overpopulation of stocked tilapia ponds and the stunting of growth because of the crowding of the fish. Another problem associated with a mix of males and females is the sizes of the fish for harvest varying from small to large due to the faster growth of males. This makes it more difficult to establish uniformity of product. For producers wanting high yields of large-sized fish in three to four months, all male fry are preferred.

Production of all male tilapia can be accomplished by such techniques as separating the males and females manually, hybridization which mates two species to produce all-male offspring, or by artificial sex reversal. The most efficient and least expensive method is sex reversal with the use of 17 alpha-methyltestosterone . . .

17 alpha-methyltestosterone is highly toxic to the human liver

. . . It has been prescribed for several years as a hormone drug substitution for men and women with hormone deficiency, and has been a favorite of body builders. The joining of the 17 alpha-methyl group to testosterone allows testosterone to pass through the liver without being metabolized. However, it also makes the drug highly toxic to the liver and capable of causing liver cancer. The drug has been taken off the market in Germany due to its high liver toxicity . . .

Hormone drug treatment of fish is restricted in other countries

. . . Many people do not want to eat food that has been altered with substances that change its basic biology. Although it can be argued that the ability of technology to provide cheap food is a good thing, new technologies often bring unintended and unwanted consequences. Little is know about the effects of the testosterone drug on the fish or on the environment. Clearly the hormone drug passes through the fish and enters environmental channels such as water and land. Unintended consequences from the use of sex changing drugs in fish would not be the first unintended consequence for the food industry. That industry thought it was a really good idea to use pulverized parts of cows in animal feed to help speed cheap food to market and fatten bottom lines. The result was cases of mad cow disease . . .

Click here to read the full article.

At Native Sun, we carry only 100% Natural Farm Raised Emerald Tilapia that is hormone free, chemical free, preservative free, and raised using sustainable farming practices.

The tilapia is cage-raised in pristine open water lakes near the mountains on Honduras. This ensures a higher water quality and flow throughout the fish’s life cycle giving it a more uniform color, taste and appearance.

Every day the water quality, feed quality and overall health of the fish are continually monitored not only for consistency, but also to track the farm’s environmental footprint. Nothing goes to waste, all used and unused packaging gets recycled weekly and 100% of the fish waste from processing fillets gets recycled and refined into biodiesel that is used to power the plant machinery, trucks and infrastructure.

This results in deep-skinned tilapia fillets that yield higher oil contents which helps to preserve the fillet’s moistness and texture from overcooking. It also creates a vibrant white and pink color, with a very smooth texture.

We believe customers have a right to know what’s in the foods they eat and the products they use, so if you have any questions about our seafood selection, vendors, country of origin, or standards, feel free to ask Phil in our Seafood Department at the Baymeadows store, or any Manager on-duty.


2 responses to “Fishy Business: Hormones Used to Cause Sex Change in Tilapia

  1. Debra Ireland

    I was very surprised to learn that the tilapia I have been buying may have the potential to further damage my liver. I contracted Hepatitis C from a blood transfusion in 1979, and am now disabled, and my physician says he sees a transplant in my future. I don’t like the sound of that at all. Information like this adds to my arsenal and helps me make choices that stack the odds in my favor. Thank you for posting this important information, and I can’t wait to visit Native Sun to try Emeral Tilapia from Honduras.

  2. This is awful to know that fish are also given Hormone drug treatment. I think it is not good for the consumers in health point of view. Such treatments should be restricted.

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