Molly eating poo

[Cmlee]

One of my Molly have been eating poo of other fishes even after feeding and it's belly is round and full
is there something wrong with it?

[Guppendler]

Pretty common actually and not just limited to mollies only

[Urban Aquaria]

It could be a sign that the food your feeding may not be fully digestible by the fishes or they are fed too much, so their poop contains alot of undigested bits of food that they still pick though to "re-eat".

Maybe you can switch to other types of fish food that have higher quality ingredients or are more compatible with your type of fishes (different fishes digestive systems are evolved to process certain foods better), and also feed less to let the fishes fully digest their food before their next meal.