Went to my LFS to check out some barbs. Then I saw the White Clouds and was ipressed with their color - much deeper red than in computer pics. They're such slender fish, does the inch per gallon rule apply to them the same as the tiger barbs I was checking out? I figured in my 18 gal. tank, less gravel and plants, I had room for 9 tiger barbs, a nice single species tank. How many clouds would be an appropriate fit in an 18 gal. tank? I would think it would be more - am I right? How many???