Display Fish Ideas For A 20?

I've recently done a tank swap and the calico fantail goldfish that were in my 20 are now in my 55 (with some new tank mates and living happily). But now the issue is what to put in my 20, there is a catfish but all he does is hide. Literally never see him. I want to put something in the tank but it has to be semi-aggressive as the catfish has been known to murder community fish. I don't think I want schooling fish, I am fairly sure I want one big fish. I do love active fish, ones with personality so he isn't hiding all the time. For me it is no fun to look at an empty tank. I do love colorful fish but I also like anything that looks ancient (like my spotted raphael catfish) or an oddball. I've browsed a few stores in my area and nothing has really caught my eye. So I'm looking for ideas?

 

what is this catfish?

 

He's a Mystus leucophasis, also known as a Giant Black Asian Upside Down Catfish. I purchased him as a Syndontis Catfish but he didn't grow with patterns. I posted on here pictures and two videos and someone identified him. While from what I read says he's community, he murdered many of my community fish before I put him in my aggressive 55 at the time. Which everyone started to get along. Now I've made the switch when my mom's convict and jewel cichlids passed. So he's alone in the 20.

 

There really aren’t any “big” fish you can keep in a 20, but as far as centerpieces go, dwarf cichlids (rams, apistos, maybe kribs) and several gourami species are suitable.

 

I do love Apistogrammas, but I would like something that is bigger than the catfish. He's about 5 inches. I don't want him to pick at them to death

 

I’ve seen a pair of keyhole cichlids in a 20 gallon long. When I passed by the tank they were very interactive and fun to watch. No idea if it they were full size or if the 20 was their grow-out tank tho, and I don't know much else about the species.

 

You actually have lots of options for larger, more aggressive and cool looking fish in a 20 gallon tank.

You could do any fish from this list.

African Butterfly Fish (Ancient looking)
Pike Livebearer (Must be male as females get too large)
Sajica cichlid (Could do a pair, Peaceful but robust)
Thalassophryne Amazonica (Not sure if compatible with your catfish)
Crenicichla Compressiceps (Dwarf Pike Cichlids - Pair only or single fish)
South American Leaf Fish (Interesting prehistoric looking fish)
Luciocephalus aura
Convicts?

You could also add a Leopard Bush Fish and use the 20 gallon as a grow out. A Leopard Bush Fish would outgrow a 20 gallon eventually though.

 

I love this website I had to look up a lot of those fish. Okay, so I like Keyhole Cichlids if anyone could tell me of that's an option. The tank does have a 40 gallon filter on it
My mom has African Butterflys and they are AMAZING, but hers kept jumping out?
The Sajicas are gorgeous! Definitely going to consider.
The Thalassophryne Amazonica is cool but I don't think he is compatible. Which sucks because he looks soooo neat.
I've never seen Leaf Fish but those would definitely be cool.
How big a tank would the leopard bush fish need?
Pretty much any of these I would have to special order because they just aren't in my area. Convicts are pretty norm and occasionally I'll see a Butterfly fish. But other than that, I've never heard of any.