Goldfish fuzz

Feb 7, 2017
Hello. I'm new to the forum and to aquariums. A little background info on my tank. It's a 40 gal that's about 4 wks into the cycling process. Unfortunately I didn't cycle before I got my fish so they've been in there since week 1 of having them. According to the pet store it was fine since its been 48 hrs...clearly not. There are 3 fantail goldfish in there.
These are the most recent values on the tetra test strips
Nitrate-about 10
Nitrite 3
Hardness 150
Chlorine 0
Alkalinity 80
pH 7.2
Ammonia .25ppm
I've been doing 25-50% water changes every other day but just yesterday started every day water changes.

I use seachem prime for the water conditioner. But recently one of my goldfish started having red blotches and is now growing white fuzz. I went back to the store to ask and he told me it's bacterial so I'm using Melfix. Just started yesterday. But I wanted to really make sure I'm treating it properly. The fish is behaving normally. Swimming fine and eating and pooping. I attached an image of the sick fish.

Hope I am doing the right things. Oh also do I have to quarantine him/her?


Last edited:


Superstar Fish
Jan 11, 2013
East Aurora, NY
I would do daily 50% water changes until you're certain the tank produces nothing but nitrates. Goldfish are often sick when you get them for the store. You've done quite well and are using a good dechlor like Prime helps detox ammonia and nitrite temporarily between daily WCs.

Likes: arcab4