There is great fishing in Panama, although, I am not an advocate of sport fishing. I think that it is horrible to hunt something just because it is the biggest out there.
There is also a world-class sail fishing and tuna fishing here in Panama. Marlin is catch and release only, but that is where the problem is. People do that because they like the fight of the fish. They fight the fish from 20 minutes to an hour to bring it in and then let it go. They promote that as being eco-friendly and non-stressful to the fish. In my opinion, if you are into big game sport fishing with a 500 pound, 8-feet long marlin and you are wearing it down to the point of exhaustion, it is stressful and potentially endangering to its life, so I am not a keen fan of that.
However, there is a great big game sport fishing here in Panama, especially on the Pacific side. There is also fabulous fishing in Lake Gatun, which is part of the Panama Canal. What people mainly catch there is peacock bass (pictured). Peacock bass is an introduced species there, so there is no limit and there is no reason not to catch them because they are not native to Panama. There are people who can bring in about 100 fish in one fishing trip, which is not even a whole day. That is usually just fishing in the morning.
There is also tarpon fishing in Lake Gatun. There is also spear fishing here in Panama, but again, I am not an advocate of that because I see a lots of times spear fishermen that break the rules. They catch a whole lot more than they can eat and that is just wasting the fish. They are going for trophies and not food. It is illegal to do any spear fishing near any coral reef in Panama because it can damage the coral.