I'm in the process of stocking a 29 gallon right now. I think a theme tank or a species tank would be cool. I once started stocking a catfish theme tank until the filter completely crashed. I had cories, upside down cats, a banjo cat and was getting ready to add some pictus or lace cats. It was a very interesting looking tank. I'm now stocking my 29 gallon with a black and white theme. I have white sand and a black background and all the fish I'm adding are black and white. I think a tiger barb/clown loach tank would look neat if you had a place to put the loaches when they out grew it.