I got a channel cat in my 150, you would need a tank with a foot print of at least 3'x3'. Channels cat get 3' BUT you're looking at a max of 2' in aquarium and 10-15lbs.
If you have space just get a pool and get alot of natives, if you dont, you can make a diy tank for cheaper. my diy drylok on osb tank only cost me 75$,i bet you can make a diy for cheap too.