3 guppies in 20g, 1 is getting bullied

Hello I have 3 guppies in a 20 gallon and the smallest guppy is picking on one of the bigger guppies. I think it is probably because the larger one has a bigger flowy tail and the little one has a skinny tail, so he is probably jealous right? I don't really want to get rid of anybody so would adding more guppies or other fish decrease the bullying? Thank you

 

What sexes?

 

What sexes?

All males

 

Can somebody help me

 

I had 5 males in a 10g, lost one to dropsy, so just the 4 now. Ive had a few nipped fins, but never anything major, and they always seem to get their pecking order worked out. If it gets really bad, grab a breeder net box, they run like $4 at walmart. Separate him into the box for an hour, let him calm down, and then try putting him back. Its basically like a timeout, and lets him know hes not the boss. Only other suggestion would be to add more decor, plants, cover, hiding places etc, which helps break line of sight and often helps with aggression. If the tank is too open, they see eachother more, and aggression could potentially happen more often.