The first-time angler to Zihuatanejo Bay may feel inhibited not knowing the rules and culture governing fishing in the bay. I too had these concerns, and so I consulted local tackle store owner Francisco Javier Lobato Ruiz. Casa Lobato Pineda tackle shop is located upstairs across from the beachfront basketball court. Unless fishing from a boat, he told me a fishing license is not required anywhere in Mexico, but be aware that fishing gear in possession while aboard a boat requires everyone on board to have a license—even non-anglers just along for the ride.
Catch and release fly-fishing, using barbless hooks as practiced in the US and Canada, is not popular among local shore fishers in Zihuatanejo. Often the fly angler can slip the catch back into the water unnoticed. Another alternative is to play the fish in close, get a satisfying look at your prize, then slack the line, and allow the fish to slip the barbless hook.
However, if a local passerby observes the release of a nice feast, the fly angler will likely be punished with a good-natured scolding, after which a promise is elicited to hand over the next prize.
Be courteous and give over the next catch. The reward will be a beaming smile, an expression of genuine gratitude, and a fine meal for the recipient.