kinda long reply
I had some Dwarf Indian Muskippers for a year or so. They were adults when I got them, wild caught of course as they do not breed in captivity. I kept them in a 55 gallon aquarium, with sloping sand, baby mangroves at one end. I had a very shallow reptile feeding dish I tried to use, but they are super messy eaters and strung food all over the place. At first I was using a small internal filter, but I had constant issues with it clogging with sand, and it wasn't really adequate for them anyway, so I got a turtle tank filter (an external small canister designed for turtle tanks). It worked great. I had driftwood and rocks for them to climb on and hide around.
They were so entertaining to watch for the first few months. One was particularly dominant and aggressive and constantly outcompeted the others for food. In hindsight, I should have removed him to his own tank. He was so aggressive that eventually the others didn't try to feed until he was off gobbling the biggest hunk he could drag away (and fiercely defend). A couple mysteriously disappeared (I can only assume they died and were eaten), I found one dead of unknown causes some months ago, and the last two I found dead just a few days ago, one on one day, the other the next, again of unknown causes. Water params were decent and they had been eating every day until the first of the last two died. The last one didn't eat that day and was dead the next. Maybe they were just old, I don't know. Either way, they were really entertaining to watch, and would have been more so, I think, if I had removed the really aggressive one.
Advice I would give is to have a secure top, they can jump like you wouldn't belive! And I highly recommend the turtle filter over an internal one.