How do you discipline a fish?

We seem to have a biting problem in our fish tank. The alpha-female ("mom" - mother to the other 5 swordtails) has taken to chasing other fish around the tank and nipping at them.

The other fish haven't picked up on this behavior yet, but I fear it's only a matter of time.

Fish are a little different than other pets. You can't really put a fish in time-out. You can't teach a fish the meaning of "no". You can't squirt them with the spray bottle. You can't put them outside until they're ready to behave.

Withholding food certainly wouldn't help with the biting problem. They'd start eating each other.

She may just be ready to give birth again. She usually starts acting really weird before she has babies.

Anybody want a naughty fish?