Freshwater Fishing??

We are working out travel plans for late December/Early January this year and I am wondering if anyone knows about Freshwater fishing in the mountains in Central El Salvador (Juayua/Tacuba?etc..) We will also be on the coast for some surfing and possible saltwater fishing, however that tends to be a lot more expensive, and also easier to find info on. I can't seem to find anything about freshwater, and there may just not be much of a market for it yet. Any advice would be helpful.. Thanks!