I'm concerned - what is it?

[Spankenstyne]

Trout is a good option as well.

[ConcinusMan]

Yeah, farmed rainbow trout or steelhead is pretty safe but still has more contaminants than tilapia.

[Spankenstyne]

True. Here's a good link that shows contaminant levels of some different fish & which ones are safer than others. It's geared towards kids but the info is great for us for our garters as well:

KidSafe Seafood - Best Choices

They've compiled data from the following sources:

Environmental Defense
Monterey Bay Aquarium
Blue Ocean Institute
Food & Drug Administration
Environmental Protection Agency
Various academic studies

There's a handy chart in the "other fish" section here:

KidSafe Seafood - Best Choices