swords3711

I have an adult male marble mollie who is extremely aggressive. He killed the other male in my bowl while I was holding on to him for another tank. He is now targeting my male red sword when eating. Why is this?

Chief_waterchanger

What size tank/bowl and how many are in the tank/bowl?

swords3711

its a 35g w/ about 20-25 fish

Chief_waterchanger

It could be overstocking issues if your fish are more than 1 inch on average or higher bioload producers, but try increasing plants and/or stuff to break the line of sight in the tank, such as driftwood, rocks, fake decorative pieces, etc.

armadillo

I had a male dalmatian sailfin molly like that, and for some reason, he would only attack my orange sailfin molly male. It got REALLY vicious, so I had to separate them. He never touches my black male, nor does my black male attack my dalmatian.

I read somewhere that mollies respected more black (considered more dominant). What colour is the bullied male?

I totally agree with the chief. Breaking the line of sight, providing lots of plants (a heavily planted area seems to really work short-term, but it's no kind of life for the bullied fish to have to live in hiding, though). Ultimately, you could look at reducing overcrowding (if you can afford to get another tank started).

Another thing you might want to try, is to turn your temp down (gradually) to 80. Mollies can get more aggressive with higher temps.

How many females do you have? Do you have 3 per male? That could improve things too.

swords3711

I had two male marble mollies and a female.
I do have two small yellow marble mollies