Ya. Rummynose show their best colors in soft (<5 dGH) waters. I think they can live in up to 12dGh, but they aren't going to be as pretty or healthy. As far as fairing in that size tank, I would be hesitant now that I see its size. If I were to keep rummynose I would want them in a large group (10+), and I'm not sure that size tank would be suited for them. Especially the larger false rummynose (Petitella georgiae
) which gets close to 3 inches long TFK profile on them
I'm a bit irked that they don't show the dimensions as length is going to make a difference here especially when talking about smaller schooling fish. I always assumed the tank was similar in size to my 30" 29 gallon, but it looks a little taller and thinner to me. Either way, for tanks of this size I think it's best to limit to 2-3 species. One substrate fish; one column swimming schooling fish; and a centerpiece fish if you so desire.
You could do a colony of sparkling gourami in there with a substrate fish.