Goldfish Got pimples

Question
Hey!
Hope you are good..well! I m in a little touble with my goldfish..she have some sort of pimples on her gills and scales as well, which are pink from bottom and off white from edges..she have pimple from a long long time from last 3 months. I tried everything for her, medicines , feed, flakes and complete water change regularly but didnt work at all...however, I have seen my sucker fish sticking on her few times..I think suckers try to clean her..
I m waiting for your answer..
Thanks!
Regards!

Answer
Hi Faiza,

Do the 'pimples' look like a sore on the fish (which does not stick out much), or does it look like a growth on the fish, (sticking out)?

If it looks like an open sore, edged in white, your fish is suffering from a bacterial infection called Erythrodermatitis. It can be treated with an anti-bacterial medication available at your local store. Before using the medication, remove any carbon from the filter and perform a 50% water change.

If it does not look like an open sore, but rather, it looks like a protrusion or growth, it may be a goiter tumor. Goiter tumors are caused by a lack of iodine and minerals in the diet for a long period of time. This often is a direct result of not feeding a high-quality food. To solve this problem, use some mineral salt (very small quantities, about one tablespoon per 5 gallons) to restore the minerals. The tumors should recede within 6 months. In the future, feed higher-quality food. Expensive is better when it comes to fish food.

If your sucker fish (most commonly Plecostomus), tries to suck at the fish, this is not good. Plecos do this (suck on the slime coats) of fish when they're starving and have nothing to eat.  This means that you are not feeding your suckermouth fish enough. Remember to buy an Algae-based food for it, like Algae Wafers. They will NOT live off the tank algae alone, they need supplements as well.

I hope this has helped you - best wishes to you and your fish!

Good Luck, and Happy Fishkeeping!