Very aggressive Male Dalmatian Molly

[LadyJRutledge]

I am stumped. I have raised molly's before but this one has me stuck. I have one male dalmatian molly, and two female molly's. One is a dalmatian and the other is gold dust lyretail molly. In addition to the molly's, I have three glow fish and two tetras (very small fish). The one male molly has become extremely aggressive. The gold molly is already pregnant. I don't know the other female is. I assumed that was the reason he was chasing the gold one. However, the other day, I caught him nudging at the bottom of the somewhat large glow fish (larger than him) the same way he does the female molly's. He aggressively headbutted the female dalmatian several times. The glow fish isn't even a molly, why would he do that to that fish. I've noticed that his large top fin stays extended lately. As if he is always excited or startled. After his attack on the glow fish, I separated him into a breeder tank within the same tank but this is getting really bad. Notes on the tank: all in a 50-gallon bow tank. Temps maintained between 78 - 80F. PH and all others tested regularly, live plants used, air filtration, etc. Since he was separated, there is peace in the tank. I don't want to let him go but, I can't allow the harassment. Not sure what to do.

[WildFish99]

One thing that could potentially help is more females to disperse his aggression a little more.

Sometimes though some fish just are more aggressive then the rest and cause trouble.