oh, my very favorite fish!
They are very active-give them lots of room.
I had them first 20 years ago, and after years without a tank, I got a 75 gallon expressly for a community built around congos. Back then I kept them with pearl gouramis, kribensis, angelfish, danios, het raspboras and corys.
Now I have them with corys, rummynose tetras and mystery snails. I plan to add rams, pearl gs and maybe an angel. They totally ignore all the other fish, never attack or pester other fish-even when the corys literally bump into them. I have 8 big males-and they are spectacular. In the evening after their dinner my boyz get into display mode. Groups of two or three will start flaring their fins and circling, then they'll take off in a race up and down the tank, sometimes with a body slam. Usually several matches are going on at once. On very rare occasions I'll see a scale tear off, but they never injure each other. The rest of the time they hang out peacefully together twitching those fabulous fins. I never saw any females at the shop where I got them (no extra appendages on the fins, according to what I've read)
Put lots of plants (mine are fake-so far) for them to swim around and through. But also leave lots of open water in the front and center for swimming and races. They usually hang out in mid and upper levels. It took them awhile to get comfortable-keep at least 6 of them.
The appendages on the fins just keep growing, and lately I've noticed mine, which I've had about six months, are getting some color tinting in the fins, a bit of purplish red. I started giving them frozen foods a couple weeks ago and maybe it's the better food or the bloodworms bringing on the color.
I lost 5 early on. I never did figure out the problem. One day one would show an abrasion on the flank, a reddish bruised area, about 1/4 inch wide, from belly to dorsal fin. Once that showed up, the fish died within hours. The others have been through two bouts of ick treatment and once for fungus-which may have been a lost scale, but I was leaving town and didn't want to tack a chance or trust the housesitter to know if it was a problem.
I can't say a single thing bad about these fish. Peaceful, easy to keep, gorgeous and interesting behavior.