What are the bug and fish vendor spawn conditions? (CJ and Flick)

CJ (fish purchaser) and Flick (bug purchaser) appear from time to time in my island town and offer better prices when selling fish/bugs.

What are their spawn conditions or do they appear randomly?


Solution 1:

They appear randomly. Except CJ does appear once every season for the tourney (and you can sell him some fish that you caught outside the tourney)