Agressive Male Swordtail!

I started this 20 gallon tank about 6 weeks ago. It was all going fine until this morning when I noticed my male swordtail was aggravating the males in the tank. He kept chasing the female swordtail and female platy. He's definetly the longest fish in the rank, but I have a male rosy barb who is much larger. I noticed now the male platy has started to fight the swordtail over and over. Whys he attacking everyone?

Pictures upon request.

 

Never kept swordtails but I do believe it is commong for the males to fight over dominance of the females

 

I had 3 male sword tails and 2 **** and the biggest one always chased the two snake ones and they died eventual cuz of stress the like to be the dominate male in the tank if he feels he not he will do that maybe u should get 2 **** to balance it out he might just chase the two **** around like mine did then they died over the amo spike and he was the only one left and he stop being like that and he was fine since hope that helps

 

How many fish do you have in the tank? I'm not sure how many you have of each, but with platys, swords, and barbs, you could very well be overstocked. Aggression is often exacerbated in overstocked tanks.

 

I also have a 55 gallon, so I moved the rosy barbs over there to reduce the amount of fish. So as of now the 20 gallon has 4 1.5 inch red eyed tetras, 1 male and female red wag platies( 1.5 inch), and 1 male and female velvet wag swordtail( 2.5 and 2 inches) I don't really think that over stocked. Another thing is, I think the only thing the male has eaten were the scraps that fell to the floor. He's pretty thin. The aggression has not stopped.

 

Here he is.