My mollies are fighting-help?

[Maltesemolly]

1. This is my first tank and these are my first fish. I have 4 mollies total. My two gold dust male mollies (I will attach pictures-please confirm if they really are male I believe they are) have gotten along since I bought them (for about 4 days) but this afternoon when I went to feed them one of the gold dust mollies started to attack my other gold dust. He has been attacking him ever since and I do not have another tank. So my question is- Should I get another tank and try to separate them? I thought mollies were suppose to be peaceful around each other. Maybe my other two mollies are female and that is why they are fighting? Or maybe it's the food? Can he really do damage to the others fins? He is specifically going after his bottom fin...I'm afraid he might get hurt.

2. I am currently using the test strips...I've just ordered the liquid testers because I don't think the strips are very accurate. But everything looks normal. Ph is 6.8

3. The tank is 20 Gallons and has been set up and running for about three weeks.

4. I'm using Aqua-tech 20-40 gallon filter.

5. I have 4 mollies, 2 small greenish catfish (not sure what they are called), and 2 ghost shrimp.

6. I did a water change about %20 and vacuumed the gravel this morning.

7. I've had the mollies for 4 days.

8. I have added nothing new to the tank since I got the fish.

9. I feed them a little twice a day and it's the tropical fish flakes

 

[Maltesemolly]

This is the molly that is biting my other gold dust



The molly being attacked






My other two mollies (female?)

 

[cjbarton1992]

Mollies are peaceful in the sense that they really don't do damage to one another. But, that being said, they are territorial fish. They establish a "pecking order", it just seems that your one male is wanting dominance over the second male. They fish in the last two pictures do appear to be female, although I could not tell 100% from the pictures. With plenty of hiding places a separate tank for the male should not be necessary. It wouldn't hurt to pick up 2+ more females to keep the quarreling down. Ideally it is 1 male for 3 females. You may even notice fights between females, but it's all over who gets to eat first. Hope this helps and that I got to all your questions!

 

[Maltesemolly]

Mollies are peaceful in the sense that they really don't do damage to one another. But, that being said, they are territorial fish. They establish a "pecking order", it just seems that your one male is wanting dominance over the second male. They fish in the last two pictures do appear to be female, although I could not tell 100% from the pictures. With plenty of hiding places a separate tank for the male should not be necessary. It wouldn't hurt to pick up 2+ more females to keep the quarreling down. Ideally it is 1 male for 3 females. You may even notice fights between females, but it's all over who gets to eat first. Hope this helps and that I got to all your questions!

Thanks, that does explain a lot. I actually noticed the two females fighting this morning. It seemed to be territorial because the one female was trying to keep the other one from coming around the little coral cave. Now whenever a molly gets close to the cave, she will go over and scare the fish away, but she doesn't seem to be hurting them.