I've read that danios are suppose to be hyperactive, but generally non aggressive fish, however i've recently noticed that two of my three basically have NO tail fin left, leading my to believe that the relatively untouched danio is to blame. The tank consists of the three of them and 3 rosey barbs, which for the most part are also untouched.

i have no idea what to do, or how to reduce the the nipping, any ideas? I'm afraid the one danio isn't going to last much longer being bullied the way it is.

With the zebra danios I had, they would often chase each other but never really hurt each other or did any damage. But, fish are individuals so they don't all behave exactly the same. Rosy barbs can also be nippy so I wouldn't rule them out. How big is the tank? What kinds of hiding places do you have? If the tank is large enough with places to hide (some wads of java moss make good hiding places), the fish being bit should be able to get out of the way. The problem with fin injury is that bacteria and/or funguses often take advantage of the situation. Once infection sets in, it can become deadly. You may need to separate some of the fish. If you can't buy another tank, you could get a net breeder which is a net that's large enough to hold a danio or two short term while they recover. To make them feel comfortable in there, add some java moss if you can get it. If the tank is large enough, adding more fish of the same species tends to make it easier on the fish being bit as there would then be more fish with which the biting fish could "play."

Good luck!

The tank is 10 gl....i have a 15gl i'm ready to switch them over too as soon as i move (across the parking lot, thankfully not far this time) and set it up. I'm then hopefully going to move my female bettas to the 10gl and free up my little 2gl for a "sick" tank if the danios need some time to recoup away from the rest o the tank.

As for hiding places...there's not much in there. Basically when i had bigger plants and various stuff in there, they basically shifted they're swimming patterns and avoided them at all costs, so i took the big ones out and used them elsewhere. Right now, there are just a few short plants, nothing else.


i'm not sure if this is normal or not either, but when i brought my original 2 dainos home, one developed an almost pot belly. When that one died i bought two more and within 2 days of being in the tank (with the original) one again developed a pot belly. Does this have anything to do with pecking order and dominance? The "pot bellied" one is the aggressor.....

Hi Max, sorry to hear about your Danio troubles.
I had 6 in my tank. They were the first fish into my 29 gallon tank, and although they are hyper, I have never seen them harm either each other or any of the other fish. I did have one that seemed to be the dominant fish, and she staked out her territory and would chase the others from it. Since they are a schooling fish I am wondering if 3 is enough? Maybe if there were a few more of them the bullying would be scattered around more and no one would get injured. Just a though.

I currently have 5 Danio's (one died last week of unknown causes), 6 neon tetra's, 4 black phantom tetra's, 4 albino cory's, 3 male fancy guppies, and 4 mystery snails in my tank.

Female danios may get a little bit fat from carrying eggs but, if you were seeing danios with really large stomachs, I'm afraid they may have had bacterial tumors, perhaps from fish tuberculosis (TB). Danios are really susceptible to fish TB. I've yet to discover a cure that works but fish can carry it for years without a problem. Once they get large tumors, it's usually a few months before they succumb. I hope your fish didn't have that.

i'm 99.9% sure its not TB. The fish has been like that since 2 days after i got it, and that was nearly a year ago, and its probably the most active and healthy looking one. I'll have to do some research into it, but it only developed after the fish established a sort of hierarchy. As for the nipping, i'm going to try to pick up a tank divider to give them some relief until i can get them in the new tank, then i'll try and see if adding to their numbers helps. thanks for all the suggestions guys!


Oh, and do i need to add more blue danios, or could i pick up some zebras and still achieve the same anti-bullying effects? Obviously, i'd like to avoid getting MORE long finned ones if possible!

So, you have two long finned blue danios? They will school and breed with zebra danios, the orange zebra danios, leopard danios, and some other variants of long or short fins danios so you can have a lot of color variety with danios.

Excellent! i can't wait to go pick out some new fish next week. This weekend however, is officially the big tank tear down and move, definetly not looking forward to that part.