PLEASE HELP ME MY OSCAR HAS A WHITE FURRY FUNGUS LIKE THING GROWING OFF HIM IN 3 SPOTS WHAT CAN I DO TO HELP HIM HE IS ONLY A FEW WEEKS OLD AND 4 CM LONG. I HAVE A BIGGER OSCAR IN THERE WITH HIM AND HE'S FINE I ALSO HAVE A YABBIE IN WITH THEM I'M WORRIED THAT WHEN THE YABBIE ATTACKED HIM THE OTHER DAY IT MIGHT HAVE CAUSED THIS. HE WON'T EAT AND ALL HE DOES IS STAY IN THE ONE SPOT HE BARLEY MOVES. SHOULD I PUT SOME SALTS IN THE TANK OR IS THERE SOMETHING ELSE I CAN DO?
I DON'T WANT TO LOOSE HIM.

A photograph is always helpful where possible. Anyway, this can be a secondary fungal infection growing on a wound but that's just a guess from your description. I would suggest using a fungal medication such as Aquarium pharmaceuticals pimafix.I would suggest that you carry out a water change and make sure that the water is in very good condition. Make sure you remove any carbon from the filtration before you medicate your tank.Hopefully a decent fungal medication will work. If the fish doesn't improve then come back to us, or better still, contact a vet

If you believe that the yabby has indeed caused an injury then I would strongly advise you to remove it. Keeping crabs with fish can be problematic as fish do have to sleep and crabs/lobsters are able to creep up on them.

also you should move your sick oscar to a hospital tank to treat him. usually a hospital tank is smaller than the main tank thereby cutting down the amout of medication needed to treat him(which is usually based on a per gallon dosage). however you would need an established filter so not to have an ammonia spike. however you treat him i wish you luck with your sick o

Any fungicide will treat the problem

The best solution from fighting is separation. I dont know what a yabby is but if it is a crab best remove. Crab and lobsters dont mix with oscars. Either the oscar have a go at them or even eat them or if they are big enought they attack the oscar