Is it normal for community fish to pick on each other?

[Stephaniem]

I have 5 zebra danio 4 guppies, 2 platys one of the danios is larger then the other ones. He chases the little ones around, and sometimes the guppies. Is this normal? Should I return the large danio?

 

[NeilS]

OMG i have the same problem...my large daino is chasing the other fish even though they're supposda be schooling...-_- but anyways...i've noticed that their fins are damaged and i don't know what to do. I've recently put in a heater so it is like 76ish and the daino kinda stopped and my fish became more active. I was going to put it into a different tank with my growafrog kit frog but i had a hard time catching him and gave up. I hope this kinda helps. hmmm...maybe the fish is like retarded or something and won't leave my other pretty fish alone... i don't know....maybe you could try glaring it down and maybe it will get the message

 

[blehblehbleh]

you might want to separate them. i knew a person who had two fish in the same tank and one fish killed the other.

 

[derekw]

I have the exact same problem with my zebra danios. at first i was alarmed to see the biggest one that i call "bertha" chasing arround the littler fish but after observing this behavior for some time i've come to the conclusion that it's completly harmless. the big danio might chase the little ones a bit, but it never actualy bites them or hurts them. also it happened all the time when i first put the fish in together but know happens less and less frequently so it could be a matter of one fish just establishing itself as the dominant one in a new environment.

you have 11 fish, how big is the tank you have for them? you need at least a 10 gallon tank for the fish you have while they are young and 20 gallons while they are adults. they might be acting more agressive because they dont have enough space maybe?