I've kept some line-bred ones as well as some wild types I brought back from Peru. Biggest challenges for sure are keeping them well fed and in very clean water. If they are missing either of the two, they will not do well. Ideally, they should have their own tank or at least be the top dog in the tank. I have noticed that they get out-competed by aggressive eaters (larger tetras, other cichlids, etc).
Another issue is aggression. A big group helps with this and with a big group goes a big tank. I tried keeping 4-5 in a 3' long 45 gallon tank and they did not do all that well. I think that the best strategy is to either go with a pair in a smaller tank (40 gal would be fine) or a group of 5+ in a 75 gal tank. You could probably get away with a 55, but they won't be happy long term.
I currently have my group of 13 in a 125 and this works well. Their only tank mates are farrowellas, whiptails and sturosoma catfish. They get 60%-75% water changes with about 75% RO water twice per week. I feed them mostly frozen beefheart, but get them to (begrudgingly) accept algae wafers and earthworm flake.
They are not particularly hard to keep if you give them the right sized tank and are diligent with water changes.
