Ok, 3 would probably be good right now for your tank size. Have you checked out craigslist.com yet? It like ebay but no fee and no bidding... no actually nothing like ebay lol.
A few hint for craigslist. Always ask to see pics and always ask to get a leak test or if the equipment works. People do have a ruff time with craigslist.
I have two pictus in my 90g, and they are suprisingly mean. They often get in tussels, and they patrol the tank like it is theirs. That is until my sunfish gets in their way and they swim away from him.
looks like a pictus if so they do well in groups of 3 or more and can reach about 4-6"
but they can have a big attitude epically towards smaller community fish they will take over an area at the bottom of the tank usually near a small low cave if you get a group those should be pretty much the only bottom feeding cat fish besides plecos they tend to bully other bottom feeders epically at feeding time beautiful cat fish when fully grown