No idea whats wrong

Question
My fish is about between 3 and 5. It lives with 4 other fish in a tank that's about 50cm wide by 35cm tall or something. It has a weird white Bump growing out of its side. I have no idea what it is. Oh, and my fish is just a goldfish, and I change the water, not very often. Probably once every two months. Please help me!

Answer
Hi April;

It may be a tumor or a cyst of some kind. Change 25% of the water right away and do it again for the next three days. This will help your fish's immune system so he can hopefully fight off whatever it is. After that, faithfully change 25% every week and vacuum the gravel at the same time. Goldfish really have a hard time staying healthy if they don't get water changes often. They are pretty messy guys.

If your other fish are goldfish they may need a bigger tank soon too. Yours is big enough for maybe two goldfish to grow in. It's hard for me to tell what the capacity of your tank is unless I have complete measurements. (Length, width and depth) Here is a great web page on goldfish and their needs;

http://www.firsttankguide.net/goldfish.php

I hope he gets better soon. Let me know how it's going...

At Your Service;
Chris Robbins