Hi all!
It looks like one of my Danios lost half of his tail. Somebody bit it. I thought that Danios are very peaceful. But it looks like that female Danios bully the others - especially I have two that are bigger than others. And their behaviour is really agressive. Can it be the case that they could bite the tail off? (It doesn't look like a rotten fin since happened just one morning.) And I have Danios only at the moment. Please, advise. What to do?
Thanks in advance,
Andrei.

Hi andrei,sorry to hear you're having trouble,i had four zebra danios in my tank and they were always chasing each other around but i never had a damaged fish,i recently added six leopard danios and all the chasing seems to have stopped,how many have you in there,if there's too few in there they'll probably keep nipping at each other,they seem to stay calmer when theres more in there


Paul

I agree you may have to few in the tank.
Keep an eye on the tail. If the cut edges start to go white or fluffy it is getting infected (fin rot) and will need to be treated.
Treatments for fin rot; Easha 2000. waterlife Myxazin. Tonic salt (available from your lfs) add 2 table spoons of tonic salt per 10 gallons of aquarium water for 1 week. You could also use the salt as a short dip but i cant remember the dosage of hand.

Strange one alright, I've seen plenty of chasing from danios but never any damage inflicted.

Looks like you have a classic "rogue" fish.

Hi all,

Thanks a lot! I have just five - bought six but one died - one night it got stuck in the filter cable channel - I found that in the morning when it was dead already.

Well, one more question - should I separate the treated fish from others and treat it in a separate tank?

Thank you in advance,
Andrei.

Hi Andrei. The chances are the damaged tail will heal it self. you will only need to treat it if it gets infected.
If you have somewhere to move it to for treatment that would be best.