My local fish store is telling me that I would be ok with 9 Neon Rosy Barbs and 6 Buenos Aires Tetras in my 29 gallon tank, but Neon's get to about 4" in aquariums and the Tetras will hit 3", so (9x4")+(6x3")=54", shouldn't I need like a 55 gallon tank for that? 
