jprime84

I know that zebra danios are active fish in any case. Here is the situation: I started the tank with two zebra danios. A week later I added a 3rd who is larger than the first two. At this point, the larger new arrival parades around the open space in the middle of the tank, and the other two lurk around plants and cover. If they stray out into the open, the big guy will quickly chase them back into submission. This happens almost constantly during the day, so I assume the smaller guys arent actually being hurt or they wouldnt go back again and again. At feeding time, there is no bickering and everyone gets a bite to eat.

Is this behavior something to worry about or will it solve itself when I add to the school after cycling is complete.

Jaysee

I think it'll stop when you add a few more.

katetnies

it might just be because he is bigger. how big is your tank. and do you have many rocks or plants in your tank

CHoffman

Danios are a schooling fish and they get insecure, nippy and aggressive when not in schools. The aggression should stop when there is 6 or more in there. Do you know your water perimeters? ammonia, nitrite and nitrate. Cycling with fish is VERY hard on the fish and even with hardy fish like danios, it can be fatal. If you have any ammonia or nitrite it would really benefit the fish and prevent damage from ammonia and nitrite poisioning if you do daily 50% water changes with Prime (it's a brand of water conditioner). There are also ways of cycling a tank without using fish. It's super easy and it's the only way I cycle tanks. Here is a link about it.

Ammonia instructions for a fishless cycle

I'm sure others will be along to give advise as well. Whatever you decide to do good luck.

jprime84

Thanks, but ive posted my water conditions several times and I am well informed on the cycle process. I already own prime and monitor my water conditions daily.


As far as the fish go, I added two other danios today hoping the group of 5 in the 20 gallon tank would behave more like a school. Well, four of them do pretty much, but that same one still chases around all of the voraciously nipping at them. One of the new ones is probably even bigger, and even it is chased. I tried to separate the aggressor to put him in another container for a bit and reintroduce him later, but I could not catch him!

CHoffman

Sorry I gave info you already had but since the perimeters and other info wasn't listed in anywhere in this thread I figured it was better safe then sorry.

Each fish has different temperaments and that's true for every kind of fish..Sounds like your danio is more like a cichlid...lol...It could be the school isn't big enough and it could be that he is just an aggressive danio and won't ever change. You can wait it out as long as he's not stressing the others to badly and add some more when you can to see if it makes a difference or you can take him back to the LFS and trade him out for a different one.

Jaysee

It a giant danio trapped in a zebras body

jprime84

They still seem to bicker now in the larger group, but it seems like it goes both ways now. I think at this point its more of a playful behavior, because even after chasing each other they still seem to school and hang out.

Shawnie

Some members that take the time to try to offer advice, dont always read all your other threads...please keep that in mind as they offer some helping information

kman

some times when danios bully other danios you need to take them out of the tank for a while and rearrange the tank so that they enter as a newfish while at others a senoirfish. helps with the pecking order