My Oscars, since I've bought them, has something like (or looks like) small woolie spots here and there on their side fins. I've treated them with "fungi stop" and some other medicine, but it stays exactly the same - what on earth can that be??

Certainly sounds like some kind of fungal infection. One of my Oscars once had this and they disappeared after a while. I know that Tetra make a product called fungistop , it might be the same stuff you have been using.. Can you possibly post some photos? What are your water readings, i.e. ammonia, nitrite and nitrate?

Just keep an eye on it and see if it gets any worse. If it doesn't, you may find that it will disappear after a while like mine did. You could of course try different medication the ones you have been using. I wouldn't keep doing them one after another, leave a little bit of time in between and do a good water change after each medication has finished. Or you could put charcoal in your filters for a few days.

Without seeing a photo, it could also be a viral infection known as "Lymphocystis" also referred to as a "lymph", which is readily identified by the whitish cauliflower like growths that grow from the fins and scales of the fish. Oscars rarely get this disease and even rarer is it fatal. Usually the growths just fall off after a long time and sometimes it takes up to a year for this to happen.

Courtesy of Aquarium Care of Oscars, by Neal Pronek and Brian M. Scott

Thank you very much for this comforting answer, I was worried sick - however, nothing seems to be wrong with their attitude Kind regards

Thank you so much for your valuable assistance - I've indeed used Tetra's fungistop but it was not succesful - I'll keep a close eye on them and call a vet out ifnecessry (I'm a bit overprotective I admit!). I've tried to download a photo, but mission unsuccessfull - will try again and also get the water readings through to you. Just for completeness sake - there is NOTHING wrong with their attitude