I'm going to Nicaragua in a month, at the end of the trip we will send a couple days on the Rio San Juan. I'm taking a couple fly rods. There are also Rainbow Bass and Snook. Anyone have any suggestions on patterns or techniques.
Take this with a grain of salt since I've only fished for tarpon once.
I had heard that tarpon can be difficult to hook due to their armor-plated mouths. So before I went to Belize, I tied some patterns on circle hooks thinking it would make things easier by taking the hook-set out of the equation. That was only half true because I forgot and yanked the hook out of the mouth of the first fish. I reacted on instinct at the sight of a giant head rising out of the water with my fly in it's mouth. Fortunately, I didn't see the second fish take, and just let it come tight before giving it a couple of good "snugs." My guide Tomas (great guide BTW) estimated the fish at about 90lbs and I fought it for close to half an hour. He was surprised it stayed on that long because it was only a 3/0 hook and the largest I had (so much for the tarpon being "small" in Belize.)
The point is if you're inexperienced with tarpon (like I was, and still am, really) patterns tied on circle hooks might be a good route. Even though I had flies tied on standard hooks in the same sizes, Tomas picked a circle hook fly. They aren't called "anzuelos automaticos" in Spanish for nothing.
Other than that, I'm not sure what patterns are good in Nicaragua. The fly Tomas picked was a Black Death tied with a purple bunny strip (not sure there's a fish that won't eat bunny strip.)