There isn't much concern with mercury and tilapia. You only need to worry about predatory fish, especially large ones. Like tuna, swordfish, large mackerel aka kingfish. But you should be concerned about where it came from and how it was farme. And the fact that you frequently aren't getting the fish you think you are.
In addition to the mercury, you also have to be aware of the ongoing Fukushima disaster. The nuclear reactor meltdown is occurring and radioactive waste is breaching directly into the pacific ocean at a rate of 93 billion becquerels per day. This has occurred every day for the last two years, and will likely continue for many more.
Be mindful of where your fish are caught, and don't overindulge.
Thank you guys for all the comments. I wish I liked salmon because I know it's really good for you, but it's one of the only meats (along with lamb) that I really dislike. I much prefer the milder fish like tilapia, flounder, and catfish. Looks like I'll be eating them a lot more often 
am sorry if am hijacking.
but since its the same topic i'll add here.
what is it to have one medium to small piece of fishes like rohu, katla, boal(wallago),Giant eyed p.d. river-catfish(called aar here),Puntio barb(punti here), tengra(am not sure what its called world wide), Mozambique tilapia(telapia here) , or parse(no idea whats its called in english.sorry)??
we dont really get salmon or tuna here.its not very common in local markets that is.
what if one has anyone of these fish curries(no they aint made as oily ans spicy as it sounds.=) ) may be around 5 days a week?
anyone?
is n't bad,eh?
aana
Thank you guys for all the comments. I wish I liked salmon because I know it's really good for you, but it's one of the only meats (along with lamb) that I really dislike. I much prefer the milder fish like tilapia, flounder, and catfish. Looks like I'll be eating them a lot more often
Are you in the U.S.? Idaho farmed trout are supposed to be good choices health, environment and sustainability-wise according to the Monteray Bay aquarium. I'm pretty sure they have to feed them fish, but it must be a lot less than goes into farming salmon.
Thank you guys for all the comments. I wish I liked salmon because I know it's really good for you, but it's one of the only meats (along with lamb) that I really dislike. I much prefer the milder fish like tilapia, flounder, and catfish. Looks like I'll be eating them a lot more often
Are you in the U.S.? Idaho farmed trout are supposed to be good choices health, environment and sustainability-wise according to the Monteray Bay aquarium. I'm pretty sure they have to feed them fish, but it must be a lot less than goes into farming salmon.
I am from the U.S. From the Houston, Texas area to be exact. I think you're from the same area? Where do you get your fish?
Thank you guys for all the comments. I wish I liked salmon because I know it's really good for you, but it's one of the only meats (along with lamb) that I really dislike. I much prefer the milder fish like tilapia, flounder, and catfish. Looks like I'll be eating them a lot more often
Are you in the U.S.? Idaho farmed trout are supposed to be good choices health, environment and sustainability-wise according to the Monteray Bay aquarium. I'm pretty sure they have to feed them fish, but it must be a lot less than goes into farming salmon.
I am from the U.S. From the Houston, Texas area to be exact. I think you're from the same area? Where do you get your fish?
Whole foods, HEB/central market, fiesta, costco, my sister who fishes in the gulf, etc. Where ever it's on sale. I don't buy it that often. I've been trying to find a great technique/recipe for cooking the whole trout. I haven't done it in a while, but most supermarkets will steam cook whatever they sell in their seafood department. The first time I tried it, I swear it was the best salmon I ever had.