Long-term bloat issue in Norman lampeye related to CO2

[confused_aquarist]

I have a wild-caught Norman lampeye that has a permanent bloat issue in the digestive tract.
It bloats up during the day and recovers overnight.
It can release bubble either by farting or by burping, but burping can cause reflux, so it has become very skinny.

When I adjust CO2 dose to 1 drop/second/100L (pH 6.5), the bloat is very severe.
When I reduce the dose to 0.5drop/second/100L (pH 6.8), it bloats much less, can digest better and is less skinny.

I've heard of a similar issue with captive-bred lampeyes and it seems to be infectious, but with mine I observe in only 1 out of 22 lampeye.
It seems to be oldest lampeye and has black dots in swim bladder.
I wonder what organ is responsible to process or release CO2?
Are there any parasites or bacteria that are known to cause this kind of issue?

 

[GaryE]

This is a curious observation - tough for the poor fish but interesting.

The swim bladders are filled with gas from the intestines, so I'll take a guess the answer lies there. I've kept a lot of lampeyes of many Genuses, and bred Guinean and Nigerian caught Poropanhax normani for many generations, but I don't use CO2.

There can be worm issues in wild caught fish of the region (not fish farm nematodes, worms easily treated with praziquantel), but I don't think swelling would come and go. I haven't seen any epidemics that caused bloating.

I'll know more about their environment in a couple of weeks as they're common in West Africa and I'll be fishing there, hoping to catch their cousins Poropanchax luxopthalmus. I'll be very surprised (and disappointed) if I don't see normani natural habitats and get precise water condition readings from them. Maybe that will give a clue. Probably not...

 

[confused_aquarist]

This is a curious observation - tough for the poor fish but interesting.

The swim bladders are filled with gas from the intestines, so I'll take a guess the answer lies there. I've kept a lot of lampeyes of many Genuses, and bred Guinean and Nigerian caught Poropanhax normani for many generations, but I don't use CO2.

There can be worm issues in wild caught fish of the region (not fish farm nematodes, worms easily treated with praziquantel), but I don't think swelling would come and go. I haven't seen any epidemics that caused bloating.

I'll know more about their environment in a couple of weeks as they're common in West Africa and I'll be fishing there, hoping to catch their cousins Poropanchax luxopthalmus. I'll be very surprised (and disappointed) if I don't see normani natural habitats and get precise water condition readings from them. Maybe that will give a clue. Probably not...

The added CO2 must be stressful for the fish, because I can see that they're required to somehow process it.

I think it's best to not use CO2 for the lampeyes, though I cannot control the pH without adding CO2. It rises to 8.0 and by then the plants are not very healthy.
For some aphyosemion fry, there's also floating issue when adding CO2. But it goes away overnight and stops after the fry grow for a few weeks. It's probably best to avoid adding it.

 

[GaryE]

It's an interesting observation and I'd be lying if I pretended to understand it completely. But it does sound like there is a connection a CO2 connection. I wonder if it's specific to killies, or if it's a result of using CO2 for pH - I've always known people to use it small amounts to feed plants.

pH is an unimportant parameter to me, in comparison to mineral content.