Radical behaviour change

[Lyrek]

I recently moved two angel fish to a hospital tank. When I moved the first one, life in the main aquarium continued as usaul.
However, once I moved the second one (a male) another male angel suddenly became intensely terrirorial. He now chases two males and the one breeding female around with a vengence right into corners.

I am worried that I have unwittingly distrupted the pecking order and hierarchy in a really bad way.
Any idea what is going on? Will it resolve itself when the two sick fish are returned? Do I now have seperate fish?

 

[ehh]

I'm sure it'll calm down once the new dominate fish has established his dominance. But I bet once you reintroduce the one in the sick tank you'll see some dominance challenges.

 

[duanes]

This is normal cichlid behavior, whenever the most dominant fish is removed, the next in line will step up and assert its dominance. It sometime works out without a casualty, but if another is also in line........
I have seen a sub-dom Paratilapia grow a nuchal hump over night, and become highly aggressive when the dominant one died.

 

[Lyrek]

This is normal cichlid behavior, whenever the most dominant fish is removed, the next in line will step up and assert its dominance. It sometime works out without a casualty, but if another is also in line........
I have seen a sub-dom Paratilapia grow a nuchal hump over night, and become highly aggressive when the dominant one died.

So it would seem size has nothing to do with it. The aggressor in this particular case is very large. The male I removed (whom apparently was dominant before) is half the size!

On another note, now that I think about it...I can't tell you for sure that the new agressor is male for sure. Is it always a male who establishes dominance? Could it be a female? There are no eggs in the tank that I can find.

Nature is...complex and interesting. Everytime you think you've figured it out, it throws you for a loop!

 

[duanes]

Females can be dominant, I have had females kill males when the males weren't ready to mate.
There is a book by Dr George Barlow called The Cichlid Fishes, Natures Grand Experiment in Evolution, that explains much about behavior, breeding, and communications, even about the sounds cichlids make.
I consider it a must have, if one is to keep cichlids of any type.