I have a 55gl and I have it based around pictus catfish. Im a sucker for the whiskers. They have a rep for being naughty little things and snacking on fish. They are hunters. This is what I did. Give you an idea.
2 spotted pictus
2 four-line pictus - these get bigger then the spotted so I would suggest staying with spotted cause mine are growing like horses! The spotted pictus grow much slower and get to about 6" the four-lines goes beyond that and their look really changes when they age.
8 Serpae tetra - good color and fun to watch.
8 White skirt tetra - pretty fish and adds a pretty white in my tank
4 glass tetra - they school with the white skirts no problem and are different to look at
3 bleeding heart tetra - school with the serpae as they look the same different colors.
1 apple snail
1 tiny black snail
1 small common pleco - I know many say you have to have a huge tank for a pleco but I dont see anything wrong with housing them, giving them a loving home and giving them back to the LFS when they get to big for your tank and starting with a small one again. IF you trust your LFS. I am unsure at this time what I plan to do for sure. I trust my LFS 100% if I take my pleco back at a larger size they will give him a good home. They have several and dont just sell them to anyone. I may be getting a large tank so I am still undecided. Depends on how much this four-lines top out at. lol
I do 50% PWC every week with my python and gravel vac every week due to the pleco poo and my four-lines being messy and bigger. This keeps my tank is great condition.
I bought these types of tetra to cut down the "risk": of them being supper to the pictus cats. There is not sure thing though, as they have been known to eat pretty good sized fish. I have had no problems though. Do not get like neon tetras though as those are the most common reported snacks for pictus cats. Tetra are common and basic so if a pictus eats them, it would be sad but I also will not be losing an expensive fish.
pictus cats hide a lot, so you need hiding spots and they come out after lights out a majority of the time. My tank looks like a tetra tank until lights out. Those times I do see my pictus come out its amazing and I enjoy it.
One of my four-lines hiding spots is under a skull, lol, I dunno what she is going to do when she cant fit under the skull anymore. The other four-line calls a wrecked ship home. My spotted pictus both hide in the logs I have in there.