why does my goldfish have a red mark on one side of its body?

Question

I have had my goldfish for 5 weeks, the past few days she has slowed down, and rarely swims around. I have noticed a red mark on one side of its body, it looks sore but I'm not sure whats wrong. I think it is missing a fin on that side. whats wrong?

I used to do a 30% water change at lease once a week, but I didnt do a full tank clean since i got it, but today is the first time I changed all the water in the tank. so maybe it was waste build up

yeh i have 2 more fish in there, and they were usually fighting after meal times. but that fighting was usually caused by my injured fish. however he is the smallest of the 3

Answer 1

Possibly inflammation. How big is the tank? Fish can have this happen when they are subjected to waste product buildup in the tank. If this is the case an antibiotic such as nifurpirinol would help. Should also mention if this is the case it could be fatal to your little friend so keep an eye on her. Hope everything turns out OK.


*Goldfish are normally not fighters but when they do get into it they usually do a little fin nipping and go back to doing their thing. Are any scales missing around the red area? Do any of the other fish show these signs? Could possibly be a parasite.

If any of these fish were purchased recently it is best to keep them alone for a few days just to be sure. Pet store fish have a habit of carrying unwanted guests into your tank.

But back to the fighting issue. Generally a fight that becomes too rough will rip off scales. Even if this is just a battle scar it would probably be a good idea to treat it before it becomes infected.

Answer 2

the other fish probably injured it

Answer 3

DO YOU HAVE MORE THAN ONE FISH????? It could be bites, either from another fish, or other aquatic menace.