Llama

I read in many places that male swordtails are hostile to each other.

Now I like swordtails so I want to get a few, will get a guy and a few girls.

However I already have platies in the tank, and I read that swords can hybrid with platies...

So do male swords fight with platies?

TFA101

In a tank your size, it should be okay to have 1 male swordtail, 3-4 females. Just so long as your tank has many places to retreat and hide, you should be okay adding your new swordtails. But since the platies are already the dominant ones in the tank (being that they were added first) I highly doubt your swords would be the ones causing problems.

Llama

So you're saying that there's going to be problems between them? I don't want to cause any trouble in the tank...

What about females? If I get 3 females on their own will anything bad happen?

TFA101

1. Platies and swords are community fish, and when they do show violence, it's usually minimal unless its a mating thing. Im just saying that if there were to be problems, I would think they would be started by the platies since they are the first ones in the tank. Not that you will have problems, but just a heads up

2. If you were to get only females, you by far reduce your risk of any aggression. If you already have some male platies, they would be occupied by the high number of females and they would divide their attentions on each female which will reduce stress when the males are courting the females (In other words, the males can't concentrate on just one female. If that were to happen, she'd be hassled to death).

Llama

Allright, I'll try to get a male sword and 3 females. The platy male is already hassling a female repeatadly... will get him another one (he's not happy with the other it seems, he hasn't chased HER around).

Moe Jacob

I have 3 swordtails (1M & 2F) plus 2 platties (1M & 1 F) in my 55 gallon, they get along like best buddies ... no probs so far and the swordtails give birth on a regular basis ... nothing from the platty yet ...