Valchitsa

I just got some Danios earlier in the week. They have already adjusted to the tank and figured out who's the leader (for the most part).. but now whenever I turn off the lights they all migrate to the top and hover around the surface as if I'm about to feed them. They do that sometimes when the lights are on too, but that usually means that they are hungry or that I'm standing too close to the tank and they think they're hungry. I have a Rainbow Shark with them and I'm thinking maybe they don't want to get near it when they can't see it very well. They swim circles around it with the lights on though. So is it the shark that's scaring them up to the surface or some other problem? Or maybe I'm over thinking everything and they are supposed to do that?

platy ben

Your shark is not scaring them dont worry, zebra danios most of the time will occupy the middle and top parts of the tank, at night they do this for safety and comfort so they feel safe in a group. .

Valchitsa

Ok good. One more question. Is it normal for one of them to go blind..? I just came home from work and noticed that one of the Danios is swimming around rather oddly, and all the other ones are picking on it. I looked closer and noticed that its eyes are white. So.. is it blind? It's also just swimming around in circles and it has its pectoral fins are sticking out like they would on an actual shark. They are flat out and parallel to the ground. I don't remember any of them being like that when I got them. So did the others do it or did nature do it?

platy ben

It could have possibly been the others, if none of the other fish have cloudy eyes, it was most likely the others.

Valchitsa

Its pretty random and mean to just pick on someone like that. The fish isn't smaller then them and it's a long fin zebra like the rest so why pick on it? I isolated it and now it's just swimming around. It is still darting back and forth as if it's ok but when it stops moving it starts to sink. Is there a chance it'll survive or is there anything I can do?

platy ben

its swim bladder may be going wrong, there isnt a cure i know of for this, the ill fish may have been the leader of your shoal beforre, but another may have got into a fight with it for dominance.

I hope your danio is ok after all this .

Valchitsa

I returned it back to the store. After being alone for a couple of hours its eyes cleared up and it started swimming like normal again. I quess the other 7 just didn't like it.. maybe it told them a bad joke. Oh well, hope that won't happen again.

platy ben

Good job on sorting the problem out