Quick drawing I did the other night of my cephadrome "Fishsticks" demonstrating the various stages prey goes through when eaten - as well as a rough overview of how long it takes for them to go through it.
Fishsticks' metabolism is geared towards tougher mons like Monoblos, so less resistant ones like say Mizutsune here can be digested in just a day or less (Mons like Monoblos, Gravios, or other sturdy mons could take several or up to a week)