Winternal paricites it is important to get the fish to eat the medication that will kill the paricites. When I last fought internal paricites I think I used what BadFishPa is talking about and to get the fish to eat it I soaked freeze-dried blood worms in it and then feed those to the fish becaue they wouldn't eat the gel drops. From what I have heard getting the fish to eat the meds is the hard part.
i gave him some type of disolveable waffer that sits in the tank and it kills all sorts of parasite( so it says ) but it seemed to have work, at least alittle, he is doing pretty good right now, soon moving into the 55 and he is going to get a girl friend!