Prolapse? What killed my Angelfish??

Hello,
I have 5 Koi Angelfish (from angels plus - IFKYK) that I have been growing out and attempting to pair off. This morning, one had what appeared to be part of its intestines/anus hanging outside of its body. It swam around like a phantom and did not eat - strangely the other Angels did not bother it at all (very odd, Angels can be very aggressive).

By this evening, after work, it was dead. No previous symptoms beyond beginning to get a thicker belly, which I presumed was egging up due to age.

The other 4 angels look great, are eating and do not appear to be ill whatsoever.

Stats:
Tank Size: 55g
Parameters:
10 Nitrate
0 Nitrite
0 Ammonia
pH: 7.8
Nothing new added to the tank. Temp 83F (for growing out).

I've attached two pictures post mortem - my good iPhone is broken so the quality is not so great.

Any ideas? I think it's a "one off" but these Angelfish are very expensive and I'd rather not make an assumption.

kribensis12 said:

This morning, one had what appeared to be part of its intestines/anus hanging outside of its body.

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I think some of my fish have had this before. Is it this string of stuff coming out of a hole close to the anus? This could be an infection and puss going out of the fish. I don't think it is contagious if I am correct. But I am not entirely sure what your fish has.
My most recent danio death was probably caused by what your fish had. Mine didn't eat, became slightly swollen and had stuff coming out from the side of it. By the time it died, it had a large hole underneath it. No medication could treat it unless maybe caught early but this happens quite quickly.
However, none of my other fish caused this "infection". I'd actually like to know myself how this happened.

Hopefully someone with more experience may know what happened to your angelfish.

A simple prolapse would be good bad news. It happens.

I see inflammation, and you are going to have to do a thorough search on Camallanus nematodes. With the fish being dead, they won't be as obvious as an advanced infestation is in a living fish. I can't see an obvious prolapse, and that concerns me.

GaryE said:

A simple prolapse would be good bad news. It happens.

I see inflammation, and you are going to have to do a thorough search on Camallanus nematodes. With the fish being dead, they won't be as obvious as an advanced infestation is in a living fish. I can't see an obvious prolapse, and that concerns me.

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I have extensive experience with Callamanus worms (unfortunately) and in my experience they are a slow killers and the red worms are easily visible from the anus.

This fish died very quickly and I have seen no evidence of worms. I do have some Metro on hand that I could mix into their flake - do you think that would be a good precaution?

I never ever use an antibiotic without certainty of what I'm treating.

Camallanus are adapting to their new aquarium hosts - not long ago they were absolute quick killers. No parasite thrives if it kills its host too soon, before it has spread. I didn't know your experience of them - I always hope you have never seen them and never will. A lot of hobbyists report prolapses when what they see are dangling Camallanus. It seemed worth mentioning - I've seen a few posts here where that mix up was in progress.

GaryE said:

I never ever use an antibiotic without certainty of what I'm treating.

Camallanus are adapting to their new aquarium hosts - not long ago they were absolute quick killers. No parasite thrives if it kills its host too soon, before it has spread. I didn't know your experience of them - I always hope you have never seen them and never will. A lot of hobbyists report prolapses when what they see are dangling Camallanus. It seemed worth mentioning - I've seen a few posts here where that mix up was in progress.

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I'm sorry, I miss-typed. I have Levisamole HCL that I could use as a dewormer. It's also known to stimulate the immune system either way. I too don't want to toss a random anti-biotic in there, especially when the remaining 4 seem very healthy.

I have, over the years, found Kribensis to be highly susceptible to Callamanus and have lost dozens of fish to it. By the time you see the worms dangling out, it's progressed pretty far and even if you kill the worm a secondary infection can easily form. While I can certainly be wrong, as I don't know what killed this fish, it does not track with my personal experience for Callamnus. A dewormer might not be a bad idea it seems.

It's one fishfarm parasite in a sea of fish farm diseases. Crowding spreads things very quickly, and the farms are under constant pressure from the chain to cut corners to reduce prices. It's an ultra-competitive market that produces weak fish as a result.
Losing one when you bought five is not a bad result for fancy angels.
Kribs are 'detritivores' and can't resist anything on the gravel, so in a farm context, that's perfect for the spread of worms and nematodes. You never see these things on wild caughts, but the farms are rotten with them.

I just had a Molly that recently passed from prolapse a few days after I finished treatment for intestinal worms, and part of his intestine were hanging out. If you don’t see signs of red worms out the anus, stringy white poop, or bloating, then it could be related to constipation. Have they have worms in the past? My theory at least why mine had prolapse, just a guess, is that the intestinal worms damaged his intestines a lot and if he got constipated, trying to poop pushed them out. What do you feed them and how often? Also, was his intestine physically hanging out or is it just the bulge like in the picture?