We also have lots of fresh tuna here in Isla Mujeres, MX. My favorites are sashimi
, spicy (raw) tuna on fresh corn tortilla chips, ceviche, cocktail, seared with sesame seeds or a good old fashion tunafish sandwich.
Squeeze lime & s&p on tuna, bake at 300 for 15 to 20 minutes. Let cool, flake add mayo and whatever you like...carrots, celery, red pepper, onion, celery salt, cucumber, ginger, soy sauce, waterchestnuts, etc. Sometimes I do just celery salt, onion & celery other times I add an asian flare. After eating "tunafish" like this I can buy canned tuna for my pets. Have fun, it's hard to get sick of fresh tuna.