Flukes appear to change form. You can see them move across the skin of the fish or protrude out of the skin. In most cases I've see with flukes attached to the skin of the fish. The fluke will almost appears to look like a little flag flapping around. I would recommend getting RODI FW dip. Get the water up to same temp which the tank the fish resides in. Also add a little baking soda to bring up the PH prior to adding the fish and use an air stone to aerate the water. Within first 3-4 minutes you should see the flukes either fall off, wiggle out of the skin or drop from the gills. Its best to use a black container of clear. Use a flashlight to confirm if you see the flukes. They should turn opaque or white. Most of them will thrash around until the FW kills them. If the flukes are present you may want to do a quick paraguard bath then start a QT with two-three rounds of prazi treatment. If the flukes are bad you may want to do FW dips every 4-5 days and definitely before adding back to your Display tank to confirm none are present still. Good luck