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Locally it is known as "el tigre de los rios", the tiger of the rivers, and Argentina's famed Dorado is a popular and sought after gamefish.
Argentina's great indigenous freshwater game fish, the Dorado (gilded in Spanish), named for its golden hue, inhabits many of the freshwaters of southern Brazil, Bolivia, Paraguay, Uruguay and northern Argentina. Locally it is also known as "el tigre de los rios", the tiger of the rivers. Together with the "Pejerrey" (fresh water silverside) they are by far the most sought after fish by Argentine anglers.
A strong swimmer
with a big mouth and powerful teeth filled jaws, it is at the top of the food chain in this river system. I have been unable to determine what the IGFA world record for Dorado is but claims for a monster weighing 31.4 kilos (69 lbs) have been made.
Its scientific name
Salminus maxillosus or Salminus brasiliensis would indicate some sort of a relationship with the salmon and trout families, but, though it has the same adipose fin, it is no relation. It is a member of the family characidae that includes numerous tropical and sub-tropical fresh water fish, including several popular aquarium fish and, according to some zoologists, the infamous Piranha.
A big head
with large gill covers are characteristics of this fish. Their powerful jaws and sharp teeth oblige careful handling and a Boca Grip or a similar tool is a useful tool to hold them while you extract hooks. Some experts say that with smaller fish they just open their mouths and pump water through the gills, virtually sucking in their prey.
They feed mainly
on fish of all types and sizes, some not much smaller than themselves and are not averse to eating small water birds and mammals such as mice, musk rats, young coypos, etc. Frogs, toads, young caimans, eels, large insects and virtually anything that moves in the water, also form part of their varied diet. They are cannibalistic; on occasion they take advantage of a hooked Dorado and many an angler has lost his catch to a bigger fellow specimen.
they are found in the Paraguay, Paraná and Uruguay Rivers and their tributaries and deltas as well as in the River Plate. In the north of the Province of Corrientes they are found in the clear waters of the Iberá and Santa Lucía marshes and the Corrientes and Santa Lucía rivers they flow into. In the north west of the country in Salta some of the great Dorado Rivers are the Juramento and Bermejo Rivers and the crystal clear waters of the Dorado River that flows through tropical jungles. Another iconic river is the Dulce that flows from the mountains of Tucumán through the Province of Santiago del Estero and into Córdoba.
At spawning time
in early summer, the female releases her eggs close to the surface and these are fertilized by three to five males that follow her. The eggs are saline so they absorb fresh water which decreases their density so they float and are carried by the currents to slower waters where 24 to 36 hours later they are hatched. For the first hours of their lives the small fish consume the proteins stored in their egg sacks and then start feeding on the zooplankton and phytoplankton found in these slack waters. As they grow, the size of their prey increases from small crustaceans and insects to other fish. The size of their mouth and digestive tract allows them to consume large prey and digest it fast. Their active metabolism requires oxygen so the larger fish can be found in the faster flowing oxygen rich waters where they also take advantage of their powerful swimming to catch their prey.
Their migrating patterns
follow the temperature of the water, they favour warm waters of between 20 and 28 degrees Celsius and in the summer can be found in the Plate estuary but as the temperature decreases they return north towards the equator. Their movements are also conditioned by the migrating patterns of one of their favoured foods, the Sábalo (Prochilodus Lineatus). This foraging fish migrates in large schools. Their flesh is fatty, in fact many years ago they were netted as feedstock for soap. The Dorados follow these schools and can be seen in groups, cornering Sábalo in shallow waters and sand banks to gorge on their high protein content. When casting to feeding Dorado, a contrasting colour of fly is perhaps the best way to call their attention to the lure, when feeding on the silver coloured Sábalo, a red, green or black fly is a good choice.
Fly fishing for Dorado
requires large flies (#1/0 to #5/0 hooks and 5 to 8 inches long). As their lays within the water column vary, a selection of weighted flies and lines is also necessary. In waters with low visibility a good profile, such as muddler heads are a good choice, but as visibility increases the designs are more demanding for colours and movement. Patterns for Dorado can be found in web sites as www.federicoprato.com.ar, www.peacockfly.com.ar and www.vistiendoanzuelos.com.
are required due to their sharp teeth and their bony jaws need a good strip strike to set the hook. (See Martin Joergensen's article "The Strike"). A short strip strike also has the advantage that if the Dorado misses the fly, it will still remain within distance for another try. As Dorado can take the moment the fly hits the water, control of the line is necessary to set the hook. Their bite is so powerful that many years ago, when I fished Dorado trolling or spinning with large metallic spoons, I have caught fish that broke their jaws taking one of these heavy lures.
Some of the rivers
I have referred to run through hard wood forests. When in flood they will wear away the banks and trees fall into the water. These submerged logs and branches are favourite Dorado lays. When fishing these rivers the fly must be placed next to these submerged trees and it is said that the ideal placing of the fly will either get a bite or snare the fly in the branches. Big upstream mends to the line are needed so that the fly, if you can call it that, would look like a small fish trying to swim upstream. When fishing "the logs" a loss of 10 to 20 flies a day is not unusual, especially when floating the faster moving waters, so a good stock of flies is needed. It is also a good idea to carry a stock of bite leaders, 30 lbs+ and 10 to 12 inches long prepared with a loop (I use a perfection loop knot) so no time is wasted when fly and bite leader have to be replaced. If you have room in your fly box an even quicker way is to have the fly already tied to the bite tippet. To keep the flies from tangling, I keep them in cellophane sleeves.
In big rivers
another good spot for trophy Dorado is where the bottom has a rocky formation, here heavy flies and fast sinking lines are needed to get as close to the rock formation as possible.
When the conditions
are right they will take over sized dry flies, big foam patterns such as variations of the Chernobyl Ant, the Fat Albert and the skating Titanic pattern. Mice and poppers of all kinds will get fantastic strikes on the surface as well. One problem I have found with dry flies is that the water displaced when the Dorado strikes can wash the fly away from their jaws.
guides and lodges offer their services for Dorado Fly Fishing in Argentina, most reputable ones have web sites.