Hi My Goldfish suddenly developed an ulcer like sore on the outside of his body it just appeared today when I got home, I am changing the water but I do need a new tank... any advice would be helpful the red sore has a sort of milky mucus layer on the top? Anything would help! He has lasted a long time and means a lot to us!

Ulcers in fish can be caused by scratches from sharp decorations and ornaments in the tank, or by parasites.

You can actually apply iodine to the wound itself to help it heal. Just gently take the fish out of the tank (not for too long obviously!) and use a Q-tip to apply some iodine before popping him back in the tank.

Parasite treatments are available from pet stores, there are a few different varieties available so it would be best to talk to the clerk about what would be best to purchase (sorry I can't recommend brands being in Australia).