You have a Saltwater tank (lobsters and sharks)? With a Catfish? If so, a little research in fishkeeping is a great idea (actually, a lot of research), because Catfish have no scales, Salt burns their skin and they won't last long. I know a few people who like the idea of catch and keep captive, and I tell them they're idiots because Coldwater tanks are quite a bit different than a Tropical Setup, and they know nothing about Aquariums to begin with (obviously CrawfishPDX has an idea about Aquaria considering he has a Saltwater tank). A coldwater tank should be between about 55-68 degrees, and should fluctuate according to season especially if your fish is/was wild. I would never put a wild fish near my water since I don't want unwanted Algaes, Parasites, or Disease.
I own a 120 gallon tank home to a 17 inch Red Belly Pacu (7-8 years old) an Adult Jack Dempsey (had for 5 years), and a 4 inch Convict Cichlid. Had many others, like Tinfoil Barbs, Plecos, Cichlids, but the Pacu feeds on any sign of weakness (tails go first, even though they are the Vegetarian Pirahna in the wild).
I know, I get a little off track from threads sometimes.