Not any line can be used to fish in the rivers of the Orinoco, and in fact there are no lines designed exclusively for this type of fishing. If we would ponder about the reasons as to why this is the case, we would see that fly fishing developed around trout fishing and even today the vast majority of fly fishermen engage in such traditional art, so the market has always been focused pretty much on designing new lines for trout fishing, and it has only been until recently that manufacturers began to develop specialized lines for fishing in tropical saltwater. For the longest time it was very hard find good lines for hot climates. As a matter of fact, the lines for cold waters become too soft in the Orinoco environment and sometimes their coating becomes doughy, in other words, line loading would be pretty much an ordeal. The best option we can find for this type fishing are lines designed for saltwater in the tropics because they have a more rigid core and its coating is more resistant.
We should note that we typically load and cast large flies, therefore the best lines to use must be designed for this purpose, always paying attention not to choose the most popular available lines for large flies that are the lines for pike as these lines are exclusively designed for cold water. Bottom line: we need tropical saltwater lines and a head section designed for large flies.
It is required to carry a floating line for fishing with poppers and other surface flies in the early hours of the morning or late in the day when peacock bass go hunting near the water surface. For fishing in the main channels of the rivers or in the deeper lagoons it is best to use sinking tip lines as they quickly take the fly to the zones where the peacocks are lurking most of the time, especially when it's sunny.
We recommend also intermediate, preferably transparent lines for fishing in the lagoons that are not very deep which need a more careful presentation. So with these three types of line you will be covering pretty much all fishing conditions. If you can only take two types of line, you better carry a floating one as your first choice and then an intermediate or floating with sinking tip, the latter depending on what makes you comfortable. I personally use sinking tip lines most of the time.
Peacock bass are not very demanding with the presentation of the fly so no thin and/or long leaders are truly needed. With a short leader of about 4 to 5 feet is sufficient to cover most situations while fishing down there, except when surface flies require a slightly better presentation, for which you will then use a leader between 6 to 7 feet long. Leaders must be made of resistant material, nylon or fluorocarbon, since a large peacock bass can easily bust a tippet of 20 pounds, and must be strong enough to handle and turn big volume wind resistant flies. You should also carry enough nylon or fluorocarbon material between 40 to 60 pounds to make the shock tippets that are needed for resisting peacocks and (especially) payara sharp teeth. Lastly if you are seriously thinking about finding (and landing) a world record, you need to take a wider variety of nylon or fluorocarbon material to make the required regulatory tippet.
Again, many thanks to Andres Parra for all his help on this article!