SAE aggression or mating?

Bill Stock wrote:

OK, so aggression is a bit overstated. They sit on the bottom and one slowly
approaches the other and it backs off. Then the one that backed off
approaches the first one and it backs off. I don't know if this is a
territorial thing or a mating ritual. It all looks pretty peaceful whatever
is happening.

I have two aquariums with SAE. In the 75 gallon the three SAE seem to
get on with each other. The bigger one does like to show its authority
every so by gently chasing the smaller two, otherwise they enjoy
swimming together. In my 24 gallon tank the three SAE hate each other
with a vengeance. Last week, one shot through a tiny hole at the back of
the tank and found it dried up and dead on the condensation glass cover.
The remaining two stay at opposite ends of the tank. Maybe its a space
issue. Or maybe its a size issue. Those three were identical in size.
How to choose a leader when they are all equal in strength and size?

Nikki