I had two a long time ago, Hara hara I believe was the species. They're pretty timid and like lots of hiding spots, I would think a planted aquarium with driftwood would be best and preferably a sand substrate. They're a stream fish, so they need higher levels of disolved oxygen and prefer a slightly lower temperature than most tropicals 70-75F with pH from mid 6's to mid 7's and soft to moderately hard water.
They're fine in a community aquarium, preferably lightly stocked with peaceful tank mates as they move around fairly slowly and are easily intimidated. I'd avoid putting them with more boisterous bottom feeders as well as they'll often allow themselves to be pushed out of the way at feeding time. As for size, mine never seemed to get much beyond 2 inches. They do like their own company so I'd recommend buying at least two.
Regarding optimum tank size, my two ended up spending most of their lives in a 2ft x 1ft x 1ft aquarium with three threadfin rainbow fish and a small bristlenose cat, they were quite happy in this arrangement although I wouldn't go with a tank any smaller than that.
