Do communal fish stress when they are alone?

[LeslieS]

Some fish like to be the only one of their species in a tank, but do fish that usually live in schools get stressed if they are kept singly?

 

[KathyC]

I know FW fish do, can't speak to SW for certain though.

 

[Bob 1000]

From my experience they seem to become very territorial, when you do decide to put another communal fish in the tank...So I guess they do get a little stressed...

 

[ellebelle]

Some fish like to be the only one of their species in a tank, but do fish that usually live in schools get stressed if they are kept singly?

I only have one B-G Chromis. When I started, I had three, but two of them died (not through the aggression of the one left alive). The one that was left spent a lot of time hiding in the back of the rocks after the other two were gone - he didn't even like to come out and eat. Once I put another fish in the tank (a wrasse, not a chromis), the chromis came out a lot more and tried to school with the wrasse. The wrasse occasionally put up with, but more often chased him away. Despite that, the Chromis spent a lot more time out from the rocks and started eating a lot better. Now he doesn't try to school with any of my other fish and zips around trying to grab as much food as possible. So, my experience is that he seemed to be stressed at first, but he kind of just .... got used to it.

Eric had the same thing sort of happen with his Chromis. Then, when he put two new Chromis in a couple of months later, the original one harassed the smallest one to death.

 

[ming]

Tangs for instance live in schools, but they seem fine alone in a tank I think. I wouldn't try putting them in a school unless you get a giant tank. Other fish school for protection, and then the threat is gone, they don't school as tight if at all.

 

[Aqua Pro Builder]

Big YES and small no.

Depends on the environment it is in, the age of them when they get to become living singly and the type of fish. Like Ming said, we need huge tank for bigger fish to school.

Let say you keep a schooling fish singly and it preceives there is danger in the surroundings. It will stress. In general, schooling fish react to threats by sensing what everyones else is reacting. For example, the fish next to it move left, it will move left as well. The decision making of most schooling fish is as a whole without a hierarchy. If living singly, it does not have the same response from other fish anymore. The best way to respond to threat is to hide in a surrending where there is no changes. Over time the health of it decrease.