WC is really based on how much experience you have with the various types of fish.... but understand that some of the rare fish... can only be caught in the wild...
Example.. wolf fish, payara, exotic peacock bass, exotic plecos, datnoids, Gars.. These are just a few examples of fish in the trade where its actually hard to breeding in a local aquarium.. and catching them in the wild is might more profitable..
As times go on... the more fish you come across you'll realize that certain fish are wild caught.. while others are farm breed.. It really just takes experience..