You appear to be offline, so I will switch to Q&A form.

First thing, you haven't mentioned if you have checked your water parameters (pH, nitrites, nitrates, ammonia). If you haven't, then I advise you do asap. Elevation in respiration can arise for a number of reason but I would be a wee bit concerned that there may be an underlying water quality issue here and this could be precipitating this.

Now the bloating you are seeing is most likely to be an abdominal distension due to dropsy, which is to say that the fish has a disturbance in his osmotic pressures that has lead to fluid accumulating in the belly. This can give them a distended appearance, raise the scales (pineconing) and can affect their general appetite and movement. Often as it advances it can give the fish difficulty swimming and lead to increased bottom sitting. Unfortunately, alone, this isn’t a sign specific to one disease. Instead, it is a later stage development in the wake of disease. Often it can by linked to advanced stages of septicaemia, intestinal flagellates, or even kidney failure in some fish.

To help your fish deal with this fluid accumulation, you will want to support them with aquarium salt. Depending on the size of your tank and the number of unaffected fish, you might consider a hospital tank for these fish. Ideally, you should used aquarium salt or non-iodised salt. With salt treatment, you usually you are aiming for a 0.3% salt concentration, which would be three teaspoons per gallon. To get to that 0.3% salt, I'd advise adding 1 teaspoon of salt per gallon of water to your tank 3 times, with each teaspoon being 12 hours after the last. When adding the salt, I usually pre-dissolve the salt in tank water before adding. And then do so slowly into a high water flow area of the tank.

In this case, for an undiagnosed dropsy, I would advise upping our tank temperature gradually till its 84 degrees Fahrenheit (do it slowly and only as long as they fish appear comfortable with the temperature increase) and covering them with a combo treatment of doxycycline/kanamycin (ideally a 2 week course). If the feces are white/mucoid then it does increase suspicions of flagelletes and these can be tackled with metronidazole, flubendazole or levaisole.

I hope this information is helpful.
Please do let me know if you have any further questions.
If you have no further questions, feedback is always appreciated.

All the best,

Dr. B.

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