fish can sense other sick fish - its fascinating

[Bubble_B0y]

I have a school of tiger barbs -
anyways there was 1 sick tiger barb.

When the sick tiger barb was in the tank - the other fish were NOT happy. They were not swimming or eating.

But as soon as I removed the sick fish, everything went back to normal.

I guess you can use the other fish to gauge how the tank is going too.

[dskidmore]

I've not heard of this happening before. Did the sick fish have some sort of open wound? Perhaps his illness somehow degraded the quality of the water.

I agree with dskidmore, something secondary may have been going on. I always do a PWC after I lose a fish or a fish gets sick.

[tropicfishman]

I noticed this to, when my recently passed away mollies got sick, I moved one to a QT tank for ICH treatment and the other one seemed to get better, I think fish can pick up on other fish's feelings liek humans can do with each other

I don't think so, but I am not argiung with you. I would like to research this. IMO, I feel that any change in behavior is due to a change in a school, community, pecking order etc. I do not believe that a fish will know if another is sick. I could be wrong, just what I think. Very interesting topic though!

[Jchillin]

Mike469, you are on the right track and this reminds me of a discussion of the topic by some of my colleagues.

Schooling fish most probably have one in the group that is able to secret or send out the Alpha phermones that give the other fish direction for schooling. If this male no longer sends out this phermone, the school is in disarray.

The same can be true of a sick fish...a phermone is released and is interpreted by the remaining fish. When we see what we think are healthy fish being "picked" on by others of the same species...is a phermone causing that?

A water change removes phermones from the water column...everything seems very peaceful for awhile afterward right?