I buy farm raised tilapia from whole foods..I think there fed fish trimmings so they do have omegs 3's. They taste pretty good. I mix the "Spectrum" mechanically organic pressed palm oil with the tilapia. Add a little kosher salt for digestion. The palm oil is white and seems to be one of the easiest oils/fats for me to digest. The red palm oil is harder for me to digest. I dont do farm-raised catfish because most of them are grain fed and the fish will be a poor source of omega 3's if the fish are grain fed. I dont think you would have mercury issues with the tilapia its a smaller fish. I also am taking a fish oil supplement along with chicken breast so i get some omega 3's.
Experiment with the oils to see what agrees with you the most..just make sure there cold pressed and dont have any bad burp ups with them.