Like I said earlier, 55 gallons is really way too small for any shark species in the long run. A 150 gallon or larger aquarium could house a Banded Cat Shark, but a 55 gallon is way off base for even that species, which by shark standards is a small fish.
If you were looking at a fish that grew slowly and would eventually, in several years time, need a large aquarium I would tell you to give it a shot. Sadly unlike many other marine fish sharks grow quickly, some obtaining up to one foot per year in size so unless that big tank is practically set-up and running they are a bad proposal for small aquariums.
I would recommend trying another fish altogether. There are some species of Lionfish, Grouper, and others that are exciting predatory fish that would make a far more active display in a 55 gallon aquarium then a banded cat shark. Sadly being that banded cats are nocturnal not only do they need a large tank they aren't very much fun. A snowflake Moray Eel would be a good option for your tank and loads more action!