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Chasing Gold: Predatory Encounters in the Iberá Marsh and Upper Rio Paraná

Fly fishing for some of the world's largest golden dorados in one of the most pristine, beautiful locations on Earth.

Chasing Gold: Predatory Encounters in the Iberá Marsh and Upper Rio Paraná

(Landon Mayer photo)

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After arriving at our camp in the Iberá Marsh in the afternoon, we decided to start right away and get in a half day of fishing. The weather had taken a turn for the worse, with storms moving in and jet-black skies in the distance. Staring at this expansive marsh, flat water, and vast shallows, I wondered what fish could be lurking out there. It was unlike any freshwater ecosystem I’d ever seen before. After some exploratory casting in a few spots—just to see if there might be fish around—we approached a long stretch of water up against a grass line that, at each bend, offered views of resting caimans, capybaras feeding on vegetation, and a giant jungle spider dangling from its web.

While I was distracted by all this beauty, a fish violently struck my fly, and a giant golden torpedo cartwheeled out of the water. My heart began to race, adrenaline rushed through my veins, and I started hyperventilating. In that moment of frantic overstimulation, my guide Marcelo Callegaris hollered at me, “Don’t be crazy, but don’t be lazy.”

Those words will remain forever in my memory. I was able to calm down, engage my fish-fighting skills, and release my first golden dorado in the Iberá Marsh with Marcelo and my boat mate. That fish maxed out the BogaGrip at more than 30 pounds. In the first two days, as our introduction to the Iberá Marsh, we boated 11 fish greater than 20 pounds among six anglers. Not only were we in one of the most pristine, beautiful locations on earth, but we had endless opportunities to catch some of the world’s largest golden dorados on fly tackle.

Collage of golden dorado fishing and lodge images.
(Landon Mayer photos)

Bucket List

A bucket list is a list of things you’ve never done but want to do before you die. Anglers need only add the word “fish.” For me, this list is forever growing and changing, but for many years, the freshwater dorado has always remained at the top of my list. This ultimate South American predator’s name means “golden” in Portuguese and Spanish. The dorado sports a salmonid shape, a beautiful paint job, and rows of incredibly sharp teeth that can scissor a fish in half or bite off a finger.

Also known as the “river tiger,” and many other names, Salminus brasiliensis is native to warm freshwater habitats in Paraguay, Uruguay, Bolivia, southern Brazil, and northern Argentina. They are jungle fish, native to the Amazon River and nearby watersheds, and they are deadly predators.

In this rainy region, home to the world’s largest river, I decided to focus my golden dorado efforts during seasonal dry periods and in watersheds with dependable conditions. So my bucket list trip was to the upper Paraná River and the Iberá Marsh in Argentina. This gave me—and the friends and clients I was traveling with—many options to fish different locations depending on water levels and clarity. Gustavo Hiebaum and his partners at SET Fly Fishing have designed a fascinating golden dorado fishing adventure that ranges from the pristine marshlands to the swift waters of the upper river, providing daily shots at golden dorados over 30 pounds.

“We have three uniquely different fishing environments, which allows our guests the opportunity to fish from two of the three lodges during a one-week visit,” said Kevin Landon, a marketing representative for SET Fly Fishing. “In the Iberá Wetlands, we have La Alondra’i Lodge, one of three remote camps located in the marsh. On the upper Paraná River, we have Itati Lodge, located on the banks of the Paraná.

“This past season, Jetu’u Lodge in the Isoro Marsh was added to our portfolio. This lodge offers the opportunity to fish a classic marsh environment created by overflow of the midsection of the Paraná River—not from rain as in the Iberá Wetlands. Access to the Paraná River also allows us to fish for numerous other species such as the pacu and pirá pitá, if the time of the season is right.”

A one-story yellow motel-style fishing lodge.
(Landon Mayer photo)

On day one of most trips, the guests are picked up in the morning at their hotel in Buenos Aires and transferred to the San Fernando Airport. From there it’s a 2½-hour flight aboard an eight-seat Cessna Grand Caravan Executive to the first destination. Guests spend four nights at the first location, with three full days of fishing.

The itinerary is Saturday to Saturday, and on Wednesday another charter flight connects guests to their second lodge.


It’s a quick 30-minute flight, so the transfer day still allows for a full day of fishing. At the conclusion of the week, the Grand Caravan returns anglers to Buenos Aires where they are transferred to the international airport for their flight home or to a downtown hotel if they are extending their visit.

This is frontier fishing, so competent and knowledgeable guides are important. Well-known fish species such as trout and tarpon have been studied for years, and numerous instructional books and articles have been written to teach anglers how to increase their odds for success. That’s not the case with dorados. Very little has been written about them, and scientists are still in the early stages of understanding their behavior, as well as their feeding and migratory patterns.

SET guides Andres Martinez, Marcelo Callegaris, Carlos Cabali, Lucas Mora, Emiliano “Salta” Basalo, and Nico Garcia are all dedicated professionals. They have countless hours on the water and share this knowledge effectively—they speak excellent English—to bring their guests up to speed as quickly as possible and get those dream fish in the net.

The cuisine at all three lodges is excellent, with a combination of both international and local flavors. Andres Martinez, co-

owner and manager, prefers to purchase as much food and produce as possible from local communities. This not only ensures that guests are dining on the freshest ingredients, but also provides support to nearby farming families.

Seasons and Weather

For protective reasons, during the spawning months of November and December, the fishery closes. The water conditions are stable and predictable throughout the season on the Upper Paraná River and the Iberá Marsh, therefore, every month fishes equally well. However, the outside temperatures and humidity are something to consider when planning your visit.

In January through mid-March it’s very warm and humid. Average daytime temperatures are in the 80s to low 90s F. and it gets down into the 70s at night. The temperatures become cooler as you move from January into March. Nighttime temperatures aren’t an issue as all common areas and bedrooms are air-conditioned.

Between mid-January and mid-February and then again between mid-March and mid-April, the pacu and pira pita feeding activity increases as these fish are omnivorous and take advantage of seasonally ripe fruit.

In late April through May, expect daytime temperatures between 70 and 80 degrees, and nighttime temperatures in the 50s and 60s F. These cooler temperatures push the smaller dorados into deeper water. This is a great time to target larger dorados but expect to catch fewer fish overall during the course of the day.

In September and October there are most often daytime temperatures between the high 70s and low 80s and nighttime temperatures in the range of 55 to 65. In this season of cooler nighttime temperatures, surface flies such as mouse and lizard patterns become super effective.

The silhouette of a fishing guide poling a boat with a pink, purple, and blue sunset in the background.
(Landon Mayer photo)

The Iberá Marsh

The indigenous communities of the wetlands in the 19th century named this area Iberá, meaning “shining water” in the Guaraní language. The Iberá Natural Reserve is one of the largest freshwater reserves in South America, and the second-largest freshwater wetlands after the Pantanal in Brazil. It is home to a staggering 4,000 plant and animal species, which make up 30 percent of Argentina’s biodiversity. Visitors here can expect to encounter caimans, anacondas, howler monkeys, capybaras, deer, otters, piranhas, pacus, and—of course—golden dorados.

The wetland is comprised of endless miles of flooded bogs, swamps, lagoons, and interconnected lakes that form prime habitat for dorados. Expansive and unspoiled, this is one of the top dorado fisheries in South America.

SET uses flat 16-foot boats to navigate and pole the wetlands, and anglers can expect to hunt by sight fishing, intercepting wakes, listening for explosions, or casting into pocketwater where you can often see the fish or unusual movement or activity that reveals their locations. On our first day of fishing, we watched a 30-pound dorado eat a smaller one 3 feet from the boat. Yes, they eat other—they eat anything that swims.

While you’re poling through the majestic waters of this marsh, you try to spot cruising dorados and cast ahead of them with baitfish patterns. Catching these amazing predators on topwater flies is also a daily opportunity. Every boat carried rods rigged with poppers, which we threw every day. It was hard to beat the visual of a popper landing on the surface, and the next second seeing a golden dorado exploding out of the water with your fly clutched in its jaws filled with razor-sharp teeth. Often these topwater strikes were within 20 feet of the boat. The noise of the poppers seemed to draw the fish toward the boat.

While hunting dorados you will also run into black piranhas. “Red eyes,” as we referred to them, are the largest and most aggressive of all piranha species, and they grow up to 10 pounds. These killing machines with knife-sharp teeth and powerful jaws make the trip feel truly exotic. Just be sure to have dozens of flies to cycle through, because a single bite from a piranha ruins a fly.

The Upper Paraná River

The Paraná River is the second-largest river in South America behind the Amazon. It’s an immense waterway, and some of the largest golden dorados in the world swim in its swift currents. Guests at Itati Lodge on the Paraná land more than 40 golden dorados over 40 pounds every year.

The lodge is located on the upper section of the river, approximately 90 miles downstream from the Yacyretá Dam. Because it’s a tailwater, this stretch of river is known for its clear and stable water flows. Such predictable fishing conditions are vital for anglers who travel internationally.

The Paraná has all the features you are familiar with on your home river—seams, back eddies, pools, riffled runs, and islands—but this magical river also has sloughs, hidden gems that you glide into slowly, pushing through lush vegetation and clumps of wildflowers into hidden lakes and ponds. You’ll also have other opportunities for casts at two omnivorous fish species—pacu and pirá pitá.

If you’re there in the right season, it’s possible to cast dry flies that imitate various fruits falling from the overhanging trees to pacus—round, dark-colored fish that have been called freshwater permit. Flowers, nuts, and other forms of vegetation, as well as minnows, are food for these “bonus” fish, and the guides carry flies to imitate these food sources. Pacus are not known for their jumping, but pound for pound are extremely powerful fighters and use their body shape to their advantage.

Pirá pitá, known locally as “salmon of the river,” are fish belonging to the Brycon genus, and they range in size from 2 to 12 pounds. Once hooked, these extremely hard-fighting gamefish are known for their acrobatic displays.

Being omnivorous, they are targeted using large attractor flies that imitate insects, fruit, mice, and even flowers. Fly fishers often cast light 6- and 7-weight rods, sometimes with “trout-ish” flies like Chubby Chernobyls and Amy’s Ants. Both pacus and pirá pitá have powerful teeth, so you must use wire tippets to land the larger specimens.

Author Landon Mayer holding a large golden dorado up for the camera, in a boat on a river.
(Landon Mayer photo)

Setting the Hook

In all destination angling, the guide takes you to where the fish are, and coaches you through the casting and presentation, but the critical moment of success is when you set the hook. With all that adrenaline and excitement—and sometimes surprise—you might forget what the guide has told you and revert back to bad habits. The most notorious bad habit in dorado fishing is, of course, the “trout set.” You’ve heard about this in saltwater fishing, but jungle fishing takes it to a whole new level.

On our first day on the water, I quickly learned that as dorados chase down your fly, they commonly eat the fly and continue swimming toward the boat. Strip-setting too soon (when you see the fly disappear) can mean a lost opportunity because you’ve already extended your line hand and have no way to adequately create hook-setting power. Instead, when you think the fish might have the fly, continue stripping the fly with the rod tip down in the water—pointing at the fish—to keep taking up slack. When you can no longer strip, wait for the fish to turn and then make two powerful hook-sets in the opposite direction to draw the hook into the corner of the mouth.

After I shared this technique with the rest of our group, we found our landing rate increased about 50 percent. We were all confident that if we could get the fish to take the fly, we could set the hook, and the first 30 seconds were ours. After that, we were just along for the ride, enjoying the acrobatic ways of these beautiful fish.

Flies & Tackle

When it comes to fly selection for adventure trips, I tend to go overboard. I usually end up with more than a dozen different patterns, and maybe three become the go-to flies for the entire week. That was certainly the case on the marshes and rivers of Argentina.

One of the big draws for this trip was not just to catch golden dorados, but to see these awesome predators smash surface flies. The Pole Dancer, Mr. Hankey, and Morrish Mouse 2.0 were all exciting surface producers. Streamers like Steve Maldonado’s Jungle Junkie on hook sizes 2/0 and 4/0 swimming just a foot or two below the surface supplied visuals that still haunt my dreams.

A colorful streamer fly with name and recipe on the right side.

Steve Maldonado's Jungle Junkie

Hook: 3/0 TMC 600 SP. Thread: Fluorescent red 6/0 Semperfli Classic Waxed. Tail: Fluorescent Yellow Bucktail. Body: Firetiger Magnum Flashabou, olive bucktail. Head: Firetiger Magnum Flashabou, Latera’s Magnum Dubbing (top), in colors Taco Tuesday, Neon Yellow, and Neon Orange. Eyes: 10mm Fly Tyers Dungeon Gold Fisch Eyes.

The dorado’s sharp teeth are an important factor, and due to the size of the flies, and the power of the fish and current, leader selection is not very difficult. Most of the time we ran 7-foot, 20- to 30-pound-test leaders with wire tippets. You can also purchase premade 20-pound test leaders with a tippet section of 35-pound-test wire.

A Scientific Anglers floating Titan Jungle Taper fly line was the only line we needed—there was never a need to sink a fly into the depths. With a Winston 10-weight Alpha+ and Bauer RX 4 reel, I was ready for battle.

One of the most important things to prioritize on a trip like this is finger and skin care. If you damage your hands, they can quickly get infected and ruin your trip. When you’re dealing with thousands of casts and line-ripping fights every day, good fishing gloves and/or taped fingers are vital. These will prevent cuts, cracks, and blisters that could hurt you later in the week.

Last but not least is a quality pair of polarized glasses. I prefer Smith Optics Guide’s Choice in copper for bright conditions, and Guide’s Choice with Ignitor low-light lenses for mornings and evenings. We caught the majority of our big fish in low light at the beginning or end of the day, or during or after thunderstorms. This is when predators prefer to hunt, and without low-light lenses, we would have missed opportunities at some big dorados.

I am grateful for every day and every adventure on the fly. This trip hosted and guided by SET Fly Fishing with my clients and friends Jim Burwell, Larry Meyer, Jason Price, Steve Cieciuch, and Bryan Webb is a custom-made trip that will have you saying: “When can I come back for more?”

Recommended Gear

The butt end of two fly rods laying on a boat; sunset in the distance.
(Landon Mayer photo)

Dorados will shred your flies and piranhas will do the same, so carry plenty of flies. Bring heavy monofilament and spools of Scientific Anglers Absolute Predator Knottable Wire to tie leaders or else bring premade Toothy Fish leaders with a nickel titanium wire tippet and a locking snap closure so you don’t have to tie the fly on and gradually lose tippet section.

Book Your Destination

Two outfitters—Andes Drifters and Parana on the Fly—joined forces to form the company SET Fly Fishing. The partners are Gustavo Hiebaum, Andres Martinez, and Marcelo Callegaris. They own five different lodges in South America.

Landon Mayer is a fly-fishing guide and Fly Fisherman contributing editor. He lives in Woodland Park, Colorado. His most recent book is Landon Mayer’s Guide Flies: Easy-to-Tie Patterns for Tough Trout (Stackpole Books, 2022).

A wader-clad fly angler kneeling and holding a large brown trout, smiling at the camera.
Get your copy of Destinations 2023 here. (Zach Heath photo)

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