If we are a little too early or too late, there is a sort of fishermen's cooperative store right across the street from the boat launch beach. The prices are amazing, and so far there has always been a good selection. Over the last couple of months the people have gotten to know us already. The store manager is more than happy to teach me about the best methods for cooking which kind of fish. They seem to stay open as long as they have fish, so it's best to go early.
Another thing that is amazing to me is that in the big supermarkets (Mega, Soriana...), they usually have frozen fish, not fresh. All the more impetus to take my daily walk or bike ride! I have a little basket on my front handlebars, and I carry a little cooler with ice. I can then put in the fresh fish, or pork, beef or chicken if I go to the mercado on the way also, and carry it all back safe and cool.
I've tried out a few new recipes, relying mostly on mangoes, limes, onion, chiles, cilantro, occasionally some cream or curry powder. Mmmm. I have not yet tried to make ceviche, as buying it is affordable and just so convenient, but I look forward to trying it out.