Are cherry barbs absolutely peaceful, or semi-aggressive? I just got a 50 gallon tank, which was bigger than I originally planned, so now I'm thinking of what other fishes I can add. I like small, colorful fishes, and already planning on putting in fancy guppies, dwarf gouramis, and platies. If you can think of other species you'd like to suggest, that would be welcome. (Nothing that is intolerant of salt, nor needs substrate, though) I'm considering tetras and danios, but I'm not too crazy about "schooling." Cories, too, but don't they need substrate?