Shark!!!

[mojoreason]

you would need a significantly larger tank to be housing a shark. and yes - it would eat your fish. it's a shark. it's not going to "fish are friends not food" courses in a sunken ship, dude.

[papagimp]

fwiw, catsharks all typically sit around doing nothing overly special. You'll never get that "jaws" feeling with a catshark. One of the local aquariums here in Oklahoma has a bunch in the kiddie petting tank (bamboo catshark). They'll just kinda lay around and may be a tad more active at night, seeing how they are nocturnal this way. Even though this is there typical behavoir, they'll still require a very large tank, not active swimmers, but still need the space. So unless you are going to have a very large shark setup with multiple specimens and the appropriate led night lighting for veieing them when active, you'll probably be somewhat disappointed in the results. I might also add that some species, such as the dog chainshark and coral catshark stay a tad smaller, about 24" instead of the 36+" that a bamboo catshark will get. But still need a good 300-500g tank.