While in Malaysia with Rompin Sailfish on Fly the guys showed us the fly they use for the pacu that have been introduced across the region and I did a fly tying how to for the channel. Even though the fish are found only in South America (and South East Asia since they were introduced in the 90s) I'm sure the fly will be deadly for other species too.
A Japan based, fly fishing blog covering a range of species from fresh water to salt.