I've been roaming around the site for a whiile now looking and reading about these fish, my roomate and i got the fish after properly cycling the 10g tank. we got 4 quarter size red bellies now and in the tank are 4 zebra danios (smaller than the red bellies) after one day it seems that the rb's are nipping each others fins more than those of the danios. is this normal? shouldn't they be more aggressive towards the other species more so than themselvs?