I just established a new planted tank and one of my new sunburst wag platys appears to have something wrong with her fins.
There are white spots that look like a small piece of fin is missing. The pectoral fin on the right side looks to be missing about a third of the fin.
It also looks like she might be pregnant as she is considerably fatter than the other platys and resembles pictures and descriptions of pregnant platys I have found.
She doesn't move around very much and stays partly hidden in the plants. When she does swim it looks ok and she eats fine.
I have only had her for a couple of days and the others that were purchased at the same time from the same tank are all ok.
Any advice is very much appreciated.
Here is a link to a picture on the spots.
Unless you have experience in fish biology, it's difficult to know what, if anything, is wrong with your fish.
My Livebearers do well with a little standard aquarium salt mixed in the replacement water. I dose a little more than a teaspoon in every 5 gallons of my new, treated tap water.
The salt will help calm the fish if it's sick, and a bit of salt in the water helps the fish breath easier. Tank water with a bit of salt in it helps gill function. If a parasite has infected your fish, then they don't tolerate even a trace of salt in the water.
I would start an aggressive water change routine, by removing and replacing half the tank water every week and add the salt dose above. I like to make the new water just a bit warmer than the rest in the tank.
The combination of a lot of pure, treated tap water and a little warmth generally is helpful. I would also feed your fish a bit of minced garlic once a week. Garlic is high in vitamins and is a natural antibiotic.
Just a couple of thoughts.