Tumor? Abscess? WTF?

[Michael from Daytona]

I have seven comets and a pleco in one of my two 600 gal connected tiled concrete ponds. They’ve been thriving for several years. I had nine, but one disappeared and another committed suicide by jumping out of the pond.

My largest (7”) comet is clearly a fatty but otherwise looks great with a super-long gossamer tail and is an active swimmer. However, I’ve been noticing the development of a small pouch-like yellow growth on both sides of the rearmost base of its dorsal fin.

I’ve seen photos of various tumor like growths in this location but all of them appear lobular and asymmetrical compared to this.

Thoughts?

 

[Mmathis]

Looks like carp pox, a benign viral growth.

 

[Mgessert]

I have one with carp pox virus, and he’s been otherwise healthy for years. We call him Lumpy. It hasn’t affected his pond mates either. If your guy has cancer, it will be rapidly progressive.

 

[Michael from Daytona]

Thanks for your replies. I investigated carp pox and its common presentation (whitish waxy looking lesions directly on the fins) doesn’t really match or resemble these lesions. I live in coastal central Florida so there’s not a classic “winter” the ponds come out of. This is the only one of my comets displaying any symptoms and given the fish is three years old I would guess it is “mature,” a time when its immune system should be keeping the pox at bay. The lesions seem stable, ie, they are not spreading or enlarging appreciably. I will continue to observe this fish for changes in its appearance or behavior.

 

[WaterGardener]

Since you have a pleco in the pond, I would wonder about him. They tend not to get along with goldfish very well.

They will be fine for a while, even years, but then start to attack the fish at night so no one realizes they are doing that. They suck the slime coat off the fish, leaving those areas susceptible to infection. This behavior seems to be fairly common with them.

If this were my pond, I would rehome the pleco.

 

[Criscar]

Thanks for your replies. I investigated carp pox and its common presentation (whitish waxy looking lesions directly on the fins) doesn’t really match or resemble these lesions. I live in coastal central Florida so there’s not a classic “winter” the ponds come out of. This is the only one of my comets displaying any symptoms and given the fish is three years old I would guess it is “mature,” a time when its immune system should be keeping the pox at bay. The lesions seem stable, ie, they are not spreading or enlarging appreciably. I will continue to observe this fish for changes in its appearance or behavior.

I live in coastal San Diego and had a mature 3-4 year old comet get carp pox this unusually cold winter for us (which was still vastly warmer than most of the ponds in this group!), but I agree that Florida spring time is not the time I would expect it. That same fish, interestingly enough, _does_ have a lesion similar to the one yours has, but in her case it is a lump of scar tissue from losing a couple scales in the area. The scar tissue is definitely far more noticeable than the original injury ever was.

 

[Mmathis]

Just an FYI, some fish can be genetically predisposed to having carp pox. Think of it as the lack of a natural immunity to a disease — some will just catch it easier than others.