Protruding operculi -- what's wrong with our fish?

[Boxworm]

Hello! We added some new fish to our pond a month or so ago. One of them had protruding operculi. I'm not exactly well-versed on fish anatomy, so just in case I've used the term wrong, I am referring to the flap that covers the gills. We were not too concerned about it because it had already been living with the other fish, and the person who sold them to us did not mention it.

However, a couple days ago, we realized another one of our fish had developed the same issue on one side. We quarantined them and are concerned about what could be wrong. They seem to be acting no differently than our other fish. What could this be? Is there a way to treat them? Should the fish in the other pond be safe now that the affected fish are removed, or will they need treatment as well?

Thanks so much for any information!!

 

[HARO]

Many years back the Chinese were developing a goldfish strain with the same affliction. The "Outfolded Operculum" was apparently a genetic abnormality, as are most "fancy" goldfish. As such it cannot be treated, is not infectious, and probably is not harmful to your fish. It can, however, be passed along when breeding. If you don't like the look, don't permit the fish to breed.
John

 

[Boxworm]

Thanks for your post, John! I have heard of this; however, what concerned me was how one fish has just recently developed it -- and only on one side. That is why I'm concerned that it could be a disease.

 

[Dave 54]

I have seen this only once in our neighbours pond on a goldfish , I dont really have a clue what causes it but the only thing we could come up with is perhaps it may be genetic in origin.. .
The goldfish lived a long and happy life and seemed uneffected by it however the gill covers can protrude not as much in the photo obviously but it is caused by a progressive build up of mucus and it caused by gill flukes which causes a discolouration of the gill filaments casuing them tostick togther .
The mucus can build up on the operculum to appear lifted this is becaue it is not able to close but I doubt your koi has this beause you dont mention any symptoms and your koi apers normal besides they dont protrude as much as in the photo.

rgrds

Dave

 

[Waterbug]

I had a fish with curled gills and a deformed mouth, favorite fish of course. I believe that was genetic, came like that as a feeder Goldfish.

But I agree, an adult fish developing curled gills, and only on one side, (and multiple fish?), I would suspect other causes. Long term poor water conditions can cause gill curling. Chronic low level nitrite would be my primary concern, but chronic low level ammonia could too. I assume chlorine could curl gills, but that's an unsubstantiated guess on my part.

Have you tested water in the past?

 

[Dave 54]

I primarily would check all your water perameters to see if you have long term water quality issues as waterbug suggests, however may I ask a few more qestion' of you ?
When did you first notice the gill casings were different to your other fish was it before or after you bought them ?.
If they dealership bought at that size did this start happening or are these koi yours from fry borm of your pond?
Do the skim flaps at the edges of the gills look any longer than many of your other fish which could be causing the gills to deform by them pushing up against the pectorals ?
One thing I would keep careful eye out for any parasite that makes the gills their home i;e gill flukes gill maggots etc by doing regular scrapes of this Koi and putting resultant mucus scraped off under the microscope.
You can do this with a credit card (we use an argos card for our scrapes) scraping backwards gently backwards from just behind the gills until you have a small sample of mucus along the leading edge of the card microscopes re nowadays relitively cheaper than back in the day. .
Find out what gill parasites ook like and store those images in your memory, because this koi would be more susceptable to gill parasites than other koi.
Other things you need keep an eye on are as follows:-
gill rot, gill damage, bacterialinfections of thkoi's gills, gill discolouration, sticky gills, gill rot gill discolouration etc.
I'm not saying any of these things will happen but forwarned is forearmed .

rgrds

Dave