goldfish with an open wound

Question
how can cure my goldfish when it has an open wound which i have no idea where did it get it? pls. i need help. it is the 4th time that this dilemma happened to me.

Answer
Hi Sen Sven;

Ulcers and open wounds on goldfish are usually caused by bacterial infections. Bacterial infection means the water needs to be changed more often and/or the tank is too small and/or overcrowded and/or overfed. Since you didn't provide any information on your tank size, other inhabitants, filtration, maintenance, etc, that's about all I can suggest at this point. Clean the tank more often and make sure your goldfish has ten gallon minimum all to itself and good filtration. Let me know more about your fish and setup and I can help more...

At Your Service;
Chris Robbins