I try to avoid farmed fish altogether. For example, farmed salmon is artificially colored, but many people buy it because of the low price. Now, I've read something about farmed catfish that has really opened my eyes.
In the April issue of the whole deal, a monthly publication from Whole Foods Market, the supermarket chain said: "Despite its popularity, typical catfish farming practices across the U.S. don't measure up to our standards. Fortunately, we found a farm that does! Our supplier partner in North Carolina raises catfish the natural way without antibiotics, hormones, algicides or land animal by-products in the feed."
What are animal by-products? They are bits of dead animals such as chickens, cows and pigs, and waste from catering businesses, restaurants and so forth that find their way into fish and animal feed. That's why it's so important to buy poultry and meat raised on a vegetarian diet.
I just Googled farmed tilapia and came across a number of entries reporting unhealthy fats in that popular fish. So stick with wild salmon (fresh or frozen), trout, sardines, anchovies and other fish.They are easy to find because markets are now required to label fresh seafood by country of origin and whether it is wild or farmed.