I have four male guppies in my tank, I was planning on getting six and originally had six but two died. But then I got a internal parasite thing that I'm still treating for and right now don't feel comfortable adding anymore to the tank until after the parasites are gone. But I've noticed that three of my four males are harassing my largest one.
My tank is 25 gallons and the water parameters are
Ammonia: 0-0.25 ppm (I know it's a little high but it will be better today)
Nitrates:40 ppm (I know once again high but once again it will be better today after the pwc)
There are three rainbows in the tank, one pleco, one striped peacock eel and some ghost shrimp and a red claw crab.
The other guppies are making this one really stressed and he's gasping down on the bottom, sometimes, though sometimes they leave him alone. There is no serious nipping at fins or scales just a lot of chasing and displaying, is there any reason and is there anything I can do to stop it? This aquarium is not planted by the way.