Just out of interest do different fish do different colours of poo? What colour is your fishes poo? Does it depend on what their diet is? What is abnormal poo? Is there a typical kind of poo that is the same for all fish?
It depends on wht you commonly feed the fish. My severums poo is green the day after I feed lettuce, and an orangish brown when he gets his meaty foods. There is a problem when your fish has clear stringy poo, most likely internal parasites