My platy keeps getting a few white spots on her tail and fin. Please see pic and note the white spot on her eye is just a reflection. There are only a few and they come and go. Some days she doesn’t have any. Other than the spots, she’s fine. The other fish in the tank haven’t been getting the spots, just her. It doesn’t look like ich to me. The water parameters are ok. What could this be? A fungus? Thanks.