I made Deborah tilapia for dinner. I decided to do a little digging on this fish because tilapia seems to be much more ubiquitous these days. I can even get tilapia sushi on Wednesdays when my Mastermind group meets. If I am going to eat it raw, I definitely want to know more about it.
Turns out, tilapia in the wild is an undesirable invasive cichlid species that eats vast amounts of plant matter, sometimes disrupting natural aquatic ecosystems, similar to Asian carp. Tilapia is sometimes used as a natural method to clear waterways of algae and plant overgrowth (SOURCE), for example in Arizona. It's an omnivorous fish, so it has been used to reduce mosquito larvae in bodies of water in malaria prone countries (SOURCE).
Its rapid growth and ability to live in overcrowded conditions has made it a popular aquaculture species (fish farming). It eats a plant based diet, so it is a less resource intensive fish to farm as compared with other species, like salmon, which require a meat based (or at least a high protein) diet. The fish yields 30-37% of it's body weight in boneless filets that are high in protein and low in calories, and the meat is firm and mild tasting (not fishy), thus popular with many consumers (and unpopular with some chefs because it lacks any distinct fish flavor).
That being said, the food used to feed farmed tilapia is often corn and soybean based so the fish is not very high in beneficial omega-3 fatty acids, as some other fish are. However, this is often true of farmed salmon as well, though the latter sometimes have omega-3s added to their feed to increase the levels. Studies have shown that fortifying tilapia feed with flax seed does improve the omega-3 profile of the meat, including the essential fatty acids EPA and DHA (SOURCE 1, SOURCE 2), but fortification is not widely used in practice for some reason I was not able to uncover.
The waste (fish poop) produced from tilapia farms is used to make fertilizer, so waste disposal is not a big issue in tilapia aquaculture. In rare cases, tilapia have been accidentally released into the wild from farms and have caused some problems.
The fresh farmed tilapia Deborah buys from Costco is sourced from sustainable aquaculture farms in Honduras, supposedly regulated for environmental safety and quality control, as described in a recent New York Times article on the fish (SOURCE). North American sources of farmed tilapia are not prevalent, in part because the fish does not survive in cold water, requiring North American producers to spend more on heating to maintain proper temperatures. Some North American producers have used warmed wastewater from power plants in tilapia farms, but this deters some consumers.
In general, responsibly sourced tilapia seems to be a good, safe, low calorie source of protein. Frozen tilapia from China has questionable safety and should probably be avoided. Sorry China!