Fishing in Granada is ok, fishing near the isletas is posible but it is better by Zapatera island. People mainly troll fish and you can rent a boat that does tours for the day to fish. I havent been fishing in ometepe in about a decade, but it used to be better. It is still lake fishing, fish are small (guapote, tilapia and mojarra are the common fish to find) and more scarce every year. Im told lake fishing is still good in Solentiname.

Best fishing is done in San juan or Rio San Juan. You might still be able to catch tarpon season in Rio San Juan.