Hi there, I understand that Cuba has some of the best salt fly fishing in the world, I remember reading about some fantastic fly fishing in a marine park but I canot remember the name of the park. I am sure a quick google search will find some great fishing but I think you may need to spend a fair amount of money to stay at the fishing resorts.
All the best
Mike.
P.S. try this link it looks good! http://www.worldwidefishing.com/cuba/b1937/index.html