I found a little one once in an aquarium ornament at a day care center. It was about 4 inches long, had been living in 2 inches of filthy water, no food, no air. Rescued it, took it home. Turned into a 10 inch terror of a digger. Amazing, the conditions some of these fish can survive in. Wild ones would be enormous. Wouldn't mind seeing some fish in their native environment, but I'm not much of a traveler.
Longshot, what part of texas do you live in? I used to live in Abilene back when I was in high school.
San Marcos, if you want to see them, bring some goggles.
I've caught all kinds of pet store critters in the rivers over here. Mostly Malaysian Trumpet snails and ram's horn apple snails, plecos, tilapia...