Re: White cloud minnow - showing a bulged belly
#2
The most likely explanation is that the fish is constipated, as evidenced in the photo by the poo sitting out from its vent but not yet dropped off.
Check out
https://www.fishkeeping.co.uk/modules/ ... esheet.php?caresheetID=73 and
https://www.seriouslyfish.com/species/tanichthys-albonubes/ for:
* an appropriate diet (eg include peas with shell removed and chopped into tiny morsels plus frozen/live foods - and try to feed little and often rather than one large meal daily) which should help;
* other aspects of care including minimum tank size to ensure that the fish gets appropriate exercise, etc.
If a more varied diet doesn't work after a fortnight or so, or if the situation gets worse in the meantime or other symptoms develop, do let us know - and we'll help further.