I have read some horror stories about tilapia from China being fed feces (and then antibiotics); there are no food regulations in China, and over 70% of the water is toxic, so any food from there is suspect.
We eat a lot of tilapia because it can be one of the most environmentally sound fish, and one of the few that can be farmed sustainably and naturally as an affordable source of protein. However, the best sources for Tilapia are reported to be the USA and Ecuador, as well as tilapia farmed in tank systems in Alberta, Canada.
Whole Foods sells tilapia from Ecuador, and has a terrific standards for seafood which can be read here. I’m generally not a Whole Foods shopper but their commitment to these standards makes their seafood very attractive; their tilapia is shown in the last photo.
We have bought a lot of frozen tilapia from Costco (the top three photos; it comes from Indonesia) and Trader Joes (photo second from the bottom; it comes from Thailand.) These are intermediary choices, but as they also come from Southeast Asia, we will be buying Ecuadorian tilapia from now on, until I can find a reliable American provider.