My personal experience with rummy noses in the past is that they nipped at my mirco swords and got ich really easily. My setup now in a 29 heavily planted is 10 Harlequin rasboras, 4 otos, and 5 bumble bee gobies. Takes a while for the harlequins to red up but once they do, they look awesome. the otos are very shy and keep to them selves all the time so they are bearly noticeable. Cause they party at night. Some of the Bumble bee gobies I know are suppoesedly brackish but I was lucky enough for my LFS to bring in some and they said they were full fresh water. They''ve been in my tank for over four months now and are as fat and happy as ever.
Sorry for the long post.