Goldfish have no true stomachs, instead part of their gastrointestinal tract has a slight widening. The food doesn't held long enough for the nutrients to become complete absorbed, unlike in animals with true stomachs like us. Therefore goldfish poop still has some nutrients left. I have read that it could take up to three times for the food/excrement to pass through goldfish' gut to be fully digested. Also, sharing their poop with each other helps them to share their beneficial bacteria. Obviously, parasites, bad bacteria and viruses use this as well, but that is entirely different subject.
|Original artwork by A.Vasiljev © 2014|
This is not an uncommon phenomenon in nature. For example, female koala feeds their newborn with her own excrement containing a cocktail of beneficial bacteria, to prepare their babies to digest toxic eucalyptus leaves.
Happy Halloween everybody!!