Why are my Zebrafish/Zebra Danios aggressive toward each other?

Question

I originally got 3, who were very hyperactive and chased each other around. I then read online that if they are not kept in large schools, they become aggressive. I bought 5 more, and they stayed together in a school and were relatively calm for about a day, but now they are back to chasing each other and biting their fins.

Help?

Answer 1

i wouldnt worry about it that much. as long as they are not hurting each other it is more of a natural play/game that these active fish do. I have seven of these and they chase each other around, but none ever get hurt.

or it could be the males chasing the females, which is normal as well.