Looks like a flagellate breakout and likely velvet.
Some behaviors associated with a fish with velvet are :
- Scratching body against hard objects
- Fish is lethargic
- Loss of appetite and weight loss
- Rapid, labored breathing
- Fins clamped against the body
- rapid breathing and mucus around the gills
Fish with velvet will typically stay at the surface of the water, or remain in a position where a steady flow of water is present in the aquarium. As the disease progresses outwards from the gills, the cysts then become visible on the fins and body. Although these cysts may appear as tiny white dots the size of a grain of salt, like the first sign of Saltwater Ich or White Spot Disease, what sets Oodinium apart from other types of ich is that at this point the fish have the appearance of being coated with what looks like a whitish or tan to golden colored, velvet-like film, thus the name Velvet Disease.
Remove fish from main tank and give them a FW dip or bath and then place them into a QT with vigorous aeration provided. Treat the fish in the QT with a copper-based medication. Although many over-the-counter remedies contain the general name as ich or ick treatments, carefully read the box to be sure it is specifically designed to target Oodinium. My choice is coppersafe at 2.25-2.5 therapuetic level at 80 degrees monitored by a reliable test kit (no api brand either)