Yeah, they get pretty large and aggressive. When theyre young they prefer a SG around 1.008, but move to full saltwater as they mature. Theyre very active fish, and big bulldozers with a big mouth to match. No shrimp, starfish, tubeworm, or crab would be safe, and neither would any fish under 3/4 the cat's length. Your profile says youve got a 20 gallon tank- that might be fine for a little while, but they will need at least a 75 as they grow (and they grow quickly)
its the columbian shark. My dads an impulse buyer and ive gotten him into the hobby. He called me a little earlier apparently he got a smaller one, and already put him in the tank. Im gonna have tio fish out tonight and take it back to the fish store. I have a couple of small fish in the tank im sure hes gonna be an a-hole.