Parrot fish with pimple on face

Question
I switched over to a 72 gallon bow front from my 55 gallon about 6 months ago. I have a parrot fish that I have had for about 6 years. I also have a brown knife fish, 4 glo fish, 2 loach, 8 neon, 2 cory cats, 3 gourami, 3 snails and a bristle nose peco. My filter is Eheim canister. I just had my water checked at the pet store and everything was right where it need to be. I used to do a 25% water change every two weeks but have since changed to doing it once a week. The parrot developed this pimple on the right side of its mouth about a week ago. It has since gotten a bit larger and kind of a purple color. She acts normal as ( as normal as a parrot can act)She is eating too. The only thing strange is everytime I go up to the tank to look at her bump she hides behind a castle,(like shes embarrassed) before she would get right in your face and follow you from side to side. All the fish seem to get along real well and she is the oldest and largest fish in the tank. She is probably around 6" long.

Answer
Hi Cindy;

She may just have a wart or it could even be a tumor of some type. There really isn't much you can do for either. Just keep the tank water very clean to help boost her immune system so she can fight it, whatever it happens to be. Do what you're doing now, a 25% water change every week. Even twice a week isn't too much. Water changes lower the nitrate levels. Nitrates suppress immunity and cause all kinds of other health issues as well.

At Your Service;
Chris Robbins