There are over 3000 recognized species of fish that are only found in the Amazon River Basin.

Expert analysis taking into consideration geographically separated species may mount to over 3500!

There are certain fishes that have such unique ecological niches that they may only be found in an area less than 50 miles square. The dynamic Amazon creates and destroys thousands of miles of river banks every year and in the process it has isolated many species to large lakes. There they evolved and branched away from their cousins as the course of the river grew ever distant from the isolated lakes.

Some thousands of years later the meander of the main river may eat its way through the flooded forest back to the isolated lake and release the endemic fish to the main channel uniting the “new” species with the rest of the aquatic fauna that exists today.

This scenario has played out over the history here in lowland Amazonia hundreds if not thousands of times. This is called geographic speciation.

Other factors that create diversity or ingenuity in survival is the fact that sometimes these isolated lakes dry up! Many fish have adapted to air breathing or gulping at the surface of water to get enough oxygen to survive. Some fish are such survivors that they can actually crawl out of the desiccating lake and make a last ditch effort to find water for example the armored catfish (Loricariidae 300+species) and the electric “eel”

(electrophorus electricus) now electrophorus vari in our area

(not really an eel but a knife fish from the family gymnotiformes )

Electric fish is by far one of the most amazing animals in the world. They use a unique system of stacked gel electrocyte cells in their bodies to concentrate an electric charge derived from the transport of sodium ions.

This species uses the electricity to stun prey and swallow them effortlessly. The mouths of these fish lack grasping teeth and actually have fleshy lobes inside that aid in O2 absorption.

The electric eels are air breathers which makes trips to the surface an obligation to gulp air. This is a wonderful adaptation for those that run the risk of drying out in a pool.

All knife fish species use some sort of electrosensory organs, as one of the most diverse groups of fish, they inhabit different niches from the depths of the river to small crystalline creeks in the headwaters.

Migrations

Amazonian fish make massive annual migrations . Every year several species of Silurids (catfish) make a 2000 mile voyage. Traveling from their nursery habitats in the Atlantic estuary to the turbulent muddy tributaries close to the foothills of the Andes. The adults will spawn in the rocky streams and slowly make their way back downsriver as the high water recedes. Other species of catfish will follow the migrating schools of their favorite prey.

The members of the Characin family migrate slightly less than the catfish and are considered more “local migrators" (less than 1000 miles) These local migrators stick around the larger tributaries and in most cases are genetically different from supposed same species from different drainage basins. The characins as well as some catfish rely heavily on the annual flooding of the forest for feeding, spawning and nursery areas.

By far one of the most amazing things about Amazonian fish is the massive annual migrations that catfish and characin species make. Every year several species of Silurids (catfish) make a 2000 mile voyage from their nursery habitats near the estuary to the turbulent muddy tributaries close to the foothills of the Andes where they will spawn and slowly make their way back downstream as the high water recedes. Other species of catfish will follow the migration of their favorite prey of the characin family. The members of the Characin family migrate slightly less than the catfish and are considered more “local migrators (less than 1000 miles) These charcins as well as some catfish rely heavily on the annual flooding of the forest for feeding, spawning and nursery areas. The flooded forest habitats are very important for healthy populations of fish

Flooded Forest

The flooded forest habitats are very important for healthy populations of fish. Unfortunately this is not recognized too much and is slowly being degraded by human activity. The black pacu and other fruit eating fish “smell” the water draining from lowland forest to calculate the density and ripeness of the fruits that fall in its waters. This is one of the reasons why lumbering flooded forest areas need to take into account, the aquatic species that rely on the rainfall of fruits. Without mature fruiting trees in the flooded areas, the fish will starve and overall an unhealthy and unproductive environment ensues.

Each flood season, the territory available to the fish is multiplied exponentially, the same place we hike in during low water is fit for a canoe during the floods, sometimes 30 ft over the low water levels.

Salty start

There is still a lot that is unknown about the fish that live in the largest river system of the world. Every year there are new species of fish discovered. Just last year two new species of pancake stingrays (Heliotrygon sp.) were found on the Nanay River. There are over 40 species and counting! Freshwater stingrays can grow to enormous sizes here in the Amazon that could reach well over the 1000lb mark. Last year, I landed a short tailed ray (Potomotrygon sp.) that tipped the scale at 163lbs.

The rays are just a small example of ocean going fish that were isolated and had to adapt to freshwater conditions.

Now about saltwater fish that adapted to fresh water, how about the bull shark

(Carcharhinus leucas. ) in 1963 a 265lb bull was caught near Iquitos with the picture to prove it! They are more frequently caught in Brazil due to the proximity to the ocean. Bull sharks have developed special osmoregulating kidneys that sense the change in salinity of the water they are in. Their kidneys inhibit the excretion of vital salts and thus recycle them throughout their body. This adaptation allows our toothy friends to move into freshwater almost indefinitely.

One of the largest fish on the Amazon is the paiche or pirarucu

(Arapaima gigas). This marvel of evolution has been around for millions of years, as adults, they can live in anoxic aquatic conditions because their blood vessel laden air bladders are modified into lungs! The paiche comes up for air normally every ten minutes or so but they can hold their “breath” much longer if needed. The juvenile paiches have much better developed gills and do not rely on this adaptation until growing up considerably. The largest recorded paiche was 10 ft long with a weight of 500lbs- once again. That does not mean that there are not larger specimens out there.

Arahuana

A smaller distant cousin to the paiche is the Arahuana (Osteoglossum bicirrhosum) this graceful swimmer is a mouth brooder, the minnows of this species stick close to the parents and when danger is lurking, the fry swim into the mouth of the caring parent. These fish are excellent jumpers, taking spiders, insects and even small birds off low perches close to the water. This fish is very valuable in the aquarium trade and there are many projects for sustainable harvest and production going on in this area for exportation

Piraiba

Another giant of the Amazon is the Piraiba or salton catfish (Brachyplathystoma filamentosum) with a record of 440lb. These giants feed on other fish that may weigh over 10 kilos! This is truly the king of the catfish because they are known to have other large catfish in their gut. Other strange stomach contents found in the salton include monkeys, although they are mainly pisciverous they will take any opportunity for a feed. I can imagine the size and weight of some Piraiba specimen could exceed 1000lb. just because one of that size has not been caught and recorded, does not mean it can’t get that large. In June of last year, I had caught a 150lb specimen on a longline while filming with Robson Greene from National Geographic’s Extreme Fishing program.

PEACOCK BASS,

Cichla monoculus, common Peruvian name, Tucunarè; size up to 12 lbs. Their explosive strike, ability to break heavy lines and straighten hooks, or drag an angler and canoe into the flooded jungle make them the Holy Grail of sport fishing.

PAYARA, GIANT WOLF FISH,

Hydrolycus scomberoides, common Peruvian name, Chambira; size up to 46 inches, and 31 lbs. Payaras possess huge fang like teeth, making Piranha look tame by comparison. Also known as vampire fish, Dracula fish or water wolf. They prefer strong current. Live piranha make the best bait, but can be taken on lures. They are very powerful, great jumpers when hooked, difficult to get in the boat, more fun to catch than to eat. Remove hook with caution.

WOLF FISH,

Hoplias malabaricus, common Peruvian name, Fasaco; size up to and over 5 lbs. Prefer shady areas, low light conditions, adapted to low oxygen conditions. A powerful predator, fun to catch, not my favorite to eat. Another toothy fish, remove hook with caution. These guys are also known as toe biters, you can imagine why.

RED-BELLIED PIRANHA,

Pygocentrus nattereri, common Peruvian name,Paña; size up and over 2lb. most notorious animal. Its powerful bite and sharp teeth can sever a finger or toe, but there are, contrary to popular belief, no confirmed fatalities resulting from a mass attack." Piranhas do not eat people, people eat piranha. Easy to catch. Use caution when handling these fish. Do not leave loose in the bottom of the boat.

BLACK PIRANHA, Serrasalmus niger, common Peruvian name, Paña Blanca; size up to 5 lbs. Handle with extreme caution.

TAMBAQUI,

Colossoma macropomum, common Peruvian name, Gamitana; size up to 80 lbs. This is a prized fish, not only for its delicious meat, but also for its great fight when hooked. Many believe the Pacu is a harder fighter than the Peacock Bass. Their teeth resemble those of the horse and are used to crush fruits and seeds.

TIGER SHOVELNOSE CATFISH,

Pseudoplatystoma tigrinum, common Peruvian name, Doncella; size up to 60 lbs. A large and powerful predator that also prefers fast moving water, not necessarily deep, they can be found in shallow water hunting the surface. These doncellas or surubim have their eyes situated at the top of their head. When migrations of smaller fish pass through, you can hear this fish snapping its mouth shut on prey close to the surface of the water. you could really confuse it with slamming shut the trunk of a car. This fish is known as a delicacy at the dinner table, one of the most used for ceviche in the Amazon.

RED-TAILED CATFISH,

Phractocephalus hemioliopterus, common Peruvian name, Pez Torre; size up to 5 ft. and over 125 lbs. Considered to be one of the prettiest catfish in the Amazon, very popular aquarium fish, and frequently caught in muddy tributaries of the Amazon river. These are the species of catfish that most rely on flooded forest habitat each year for fattening up on valuable fruits such as ayauma Couroupita or cannonball tree

DORADO CATFISH,

Brachyplatystoma flavicans, common Peruvian name, Dorado; size up to 4 ft., 70 lbs. the most impressive migrator of all silurids here. is the most delicious of the region’s catfish. These fellows nursery area is in the estuary of the Amazon river until they reach a decent size for them to start migrating upstream for spawning and feeding. The Leticia-Iquitos area has the highest catch rate of adult individuals

GIANT CLAWED CATFISH,

Pseudodora niger, common Peruvian name, Turushuqui; size up to 50 lbs. Nocturnal, Distinctive rows of claw-like bony protuberances along each side. Armored, prehistoric looking, hard fighting, delicious. it would be tough though to get one of these to bite your hook, they mainly eat rotting wood material. they are very common

OSCAR, Astronotus ocellatus,

common Peruvian name, Acarahuasú; size up to 3 lbs. The supreme pan fish of the upper Amazon. Very delicious. Popular aquarium fish, great fighters. They prefer log jams, tree falls and floating vegetation. Whenever I catch one that is worth eating, I always think how much people pay for a full size live Oscar for their fish tank, and I claim that I am eating the most expensive meal in the Amazon