The only real threat in the Lavaca Bay area is methylmercury(mehg) that may be in higher doses than normal because Alcoa was discharging about 67lbs of metal mercury(Hg) into the bay from the smelters.
From what I've heard, since the $40 million cleanup the fish in the lavaca bay are no more contaminated than your average freshwater fish in Texas. The freshwater fish are getting it from the coal power plants. It's also in the air we all breath.
I eat the fish and don't worry about it, but also only eat fish about once a month or so. If I were planning on raising a new family here(happily married with all teenagers) I would NOT let my wife eat the fish if she were pregnant or expecting to get that way in the near future. (for the sake of my children not to starve her)
Also, the more finfish the predator fish eats the more MeHg it will be contaminated with. Young fish will be less contaminated than older bigger fish. (they mainly get it from eating fish that eat algae)
Here's a pretty extreme picture for any oyster lovers out there. I for one will not be ordering oysters for a while at restaurants. These guys are harvesting them right at the boundary and looks like a couple are actually inside the zone. Seems like a really bad place to be harvesting oysters, when they were the first thing banned when the problem became evident.