Zebra Danios fin nipping?

[Kryten]

I have just put my first fish into a newly cycled 20 gallon tank. I have two painted platy's and three zebra danios. However, the zebra danios seem to be chasing each other and appear to fin nip the smallest of the three. Is this likely to be fin nipping or could it simply be randy fish?

 

[bigfish]

More likely that you have 3 males!!! be careful that the smaller one dont get bullied to much as the two bigger ones might kill it as part of there natural instincts.

 

[Kryten]

Will it help putting a female in. I was thinking about putting a leopard danio in, are these a different strain if the same fish, so would three males be happy with a female leopard danio, or will it have to be a zebra danio.