Platy's fins are clamped?

Hey guys I just put 2 red platys in my tank a couple of nights ago. one is doing fine but I noticed that the other ones fins are clamped. I have a 20 gallon tank, ammonia is 0 nitrite is 0 and nitrate is about 20ppm. water temp is around 78-80. any info would be great.

 

What is your water change schedule?

I would do at least a 25% change asap.

 

I do a 25% change every other day, and since I noticed the problem ive changed it to every day.

 

I also just noticed he's kinda flicking himself against things like rocks, plants, etc...

 

Size of tank?
Other fish?
Any new introductions?

 

20 gal tank, with one angel and 1 gourami. the newest additions to the tank are the platys

 

Check the symptoms against those listed at this link:
& see if you find a matching disease. He's flashing with clamped fins, so i'm pretty sure he's got a disease of some kind, but you might find it faster looking at the chart than me asking you a bunch of questions on any other symptoms he's showing.