A very aggressive Zebra danio in the group...

[Florida8]

Not sure what's going on. I bought 6, they gave me 7, zebra danios for my daughters planted mini bow... there are a few with the longer fins and then the other 4 have the shorter fins. Are these a different species and could this be a problem?

There is on that is bigger than the rest, much darker markings and a lot of yellow ... this one keep chasing the other fish, not playful either, nippings fins ... is there a reason for this? Are the darker markings & brighter colors signs of anything?

Tank is over a year old and fully cycled and perfect water, the fish are great aside of the bully danio... remove him or will it settle down? I have had them many times over the years and they never did this.

TIA

 

[dskidmore]

Dannios are often agressive fin nippers. You may have luck taking out the dominant one, or you may just end up with the next guy down on the totem pole doing the same thing.

How large is the mini-bow? Are they crowded?

The long and short fins are likely from diffrent breeders but the same species.

 

[shaunakadub]

I'd say make sure they are fin nipping and not playing tag. I have a few zebra's that on first sight, one would think they are bullying the crap out of each other, but if you take a closer look, thier fins are in perfect condition, which leads me to belive they are just playing some sort of fish tag.

 

[TomK2]

Well, danios spend most of thier time chasing each other around, so that it is good that you have 7 of them to spread around the action. I bet this is normal danio behavior. With some planted areas for the fish to rest in, I bet everything settles down. If you really feel you have a bully, a few days in a QT could calm him down.