By Peter Petersen

Rio Ucayali

Driftwood in Rio Ucayali in the end of rainy season.

A pair of the Ucayali blackline catfish Pimelodella hartwelli caught where the Rio Ucayali meets Rio Pacaya.

I guess it's fish for dinner. Rio Ucayali is rich in fish species and even during rainy season itś easy to fill up the canoe.

These boxes are used to transport fish for the aquarium trade. The boxes are coating with plastic bags and are open in the top. During the trip, the fishermen stops to change water regularly.

Here are some juvenile Arowana Osteoglossum bicirrhosum being exported to the Asian marked.

Sometimes the fry of the Arowana Osteoglossum bicirrhosum still have a yolk sac. They will not eat untill the sac is gone (used).

Local fishermen are usually very friendly and will often help you find interesting species. 

The indigenous people keep a lot of pets. These white-winged parakeets Brotogeris versicolurus I noticed in a nearby house.

Changing water levels creates ideal conditions for floating plants like water hyacinth Eichhornia crassipes, water lettuce Pistia stratiotes, Mimosa amphibium, water spangles Salvinia minima and water grass Hygroryza aristata.

These floating islands of aquatic plants, branches and roots are ideal hiding places for fish. This kind of moving habitat is definately worth exploring. They often reveal new interesting species.


 The peruvian blue sole Apionichthys nattereri. This rare fish was caught in Rio Ucayali near the village of Bretaña.

This festive amazon parrot Amazona festiva was kept as a pet by a family in the small village Bretaña.

Another family kept this Brown woolly monkey Lagothrix lagothricha. The local people have a very strong connection to the rainforest and the animals living here.

The house we stayed in, had many interesting inhabitans like this Giant Crab Spider Heteropoda venatoria

We left the door open while we unpacked our luggage and this Red Snouted Treefrog Scinax ruber came in to say hello.

Under the bed we found a ball and this Giant Toad Rhinella horribilis.

Simple local food: Banana chips and the Peacock Bass Cichla monoculus.

Banana chips and the Peacock Bass Cichla monoculus is the Peruvian version of fish and chips.

Rio Pacaya

Rio Pacaya in Pacaya Samiria is an unspoiled jewel of the Amazon. Dense impenetrable rainforest makes the rivers the only way to travel to this amazing place.

 I caught this serated silver catfish (Auchenipterus ambyiacus) in Rio Pacaya. The water was very cloudy in this slow moving part of the river.

This South American freshwater stingray (Potamotrygon motoro) is the most common in the region. Only adults have the ocellated rings. 

Amazon Cichlid (Cichlasoma amazonarum) feeding on unidentified freshwater shrimps and using water lettuce (Pistia stratiotes) and water spangles (Salvinia minima) as a hiding place.

This thorny catfish (Nemadoras humeralis) was caught in the shallow water (around 30 cm deep)

The floaded forest provides lots of hiding places and food items for the many fish that lives here and the diversity is amazing.

The Barred sorubim catfish (Pseudoplatystoma fasciatum) is one of the larger predators here. They patrol the edge of the shade provided by the floating water lettuce (Pistia stratiotes) and water spangles (Salvinia minima).

The Small Sharpbite Tetra (Oxybrycon parvulus) we observed in small schools of around 8-12 individuals eating ants and flies from the water surface.

Rio Pacaya is a blackwater river which run in to the Pacaya Samiria.

The Payara Hydrolycus armatus is one of the largest predator fish here. This youngster can grow to more than 1 meter.

Possibly the Arimaspi Headstander (Leporinus arimaspi) were a common fish in Pacaya Samiria. I observed them eating detritus and roots of the the floating plant water lettuce (Pistia stratiotes).

The giant talking catfish Megalodoras uranoscopus is also present here. Juveniles like this one have amazing contrast in coloration.

The Hoatzin (Opisthocomus hoazin) is terrible at flying. But the chicks have an amazing adaptation to life in a flooded rainforest. They have claws on their wings so that they can climb trees if they fall from the nest.

Young Redtail catfish Phractocephalus hemioliopterus are beautiful. The yellow and red coloration is incrediable. 

During rainy season the rivers floods the forest and the rainforest floor becomes habitat for thousands of fish species.

This South American catfish (Rhamdia quelen) is quite common in Pacaya Samiria. This species hunts small fish and shrimps belonging to the genus Macrobrachium.

The rainforest is so dense in some regions that it is almost impossible to get the boat through or even walk on the forest floor without the use of a machete.

This Oscar cichlid Astronotus ocellatus was caught in the flooded forest in shallow waters. The individuals we found in this area all had ocellated rings (5-7) high up in the dorsal fin. 

Young Firewood catfish Sorubimichthys planiceps like this one I usually found in the shallow waters amoung the floating plants. 

While catching fish I came across this Bocourts Ameiva Medopheos edracanthus eating ants on a tree trunk hanging over the river.

Pimelodid catfishes (among others) dying in the Rio Pacaya in Pacaya Samiria. Skimming the surface for oxygen. The rainy season starts and releases toxic gasses from the mud bottom.

Pimelodid and doradid catfishes in the shallow waters of Rio Pacaya: Zamurito Catfish Calophysus macropterus, Giant Talking Catfish Megalodoras uranoscopus and Blochs Catfish Pimelodus blochii.

All fish are affected by these conditions. This South American freshwater stingray Potamotrygon motoro is also taking it's last breath.

This habitat is home to a common catfish in the aquarium trade. They are perfectly camouflaged even in the shallows waters. They trust their own ability to blend in and do not move even if you touch them.

Two Chocolate-colored catfish Rineloricaria lanceolata and a group of young Blochs Catfish Pimelodus blochii enjoying the shade from a tree trunk.

A closer look reveals a school of unidentified shrimps passing by the Chocolate-colored catfish Rineloricaria lanceolata and the young Blochs Catfish Pimelodus blochii.

I observed Chocolate-colored catfish Rineloricaria lanceolata foraging for hours. I only saw them eating detritus (Dead particulate organic material). This could explain why these wild fish are thinner than those kept in aquariums.

Previous waterlevels have marked the roots of the rainforest trees. Here the level difference is only about a meter. Sometimes the water raises and drops more than 7 meters from dry to rainy season. 

Floating aquatic plant like this Ludwigia helminthorrhiza are perfectly adapted to the drastic rise and fall of waterlevels.

This young Corvina Plagioscion montei is only 3 cm long and were caught deep in the Pacaya Samaria rainforest.

I rarely came across this species. Even though they should be quite common here. I observed the Corvina Plagioscion montei chasing schools of small unidentified shrimps.

A common aquatic gastropod in this region is the spike-topped apple snail Pomacea diffusa. The place their pink eggs in vegetation above water to protect them from predators.

The Swallowtail pimeloid Platysilurus mucosus are also present in Rio Pacaya. We found these most common in a depth of 1-2 meters. Most specimens we found were in this size.

Flood rainforest.

ocelot (Leopardus pardalis)

A very shy species of cat also lives here deep in the rainforest. This is the ocelot Leopardus pardalis. 

Young Duckbill catfish Sorubim lima have very elongated caudal fins. We found them often under floating vegetation near the flooded rainforest.

In this bromelia we noticed some dartfrogs of an unidentified species. We heard them call a number of times but the bromelia was too high in the tree to get a proper look at the specimens.

The national reserve of Pacaya Samiria is providing the local people with food. They do not have refrigerators so they use salt to preserve the fish for later consumption.

Rio Nanay


Rio Nanay with floating islands of water hyacinth Eichhornia crassipes, water lettuce Pistia stratiotes and water grass Hygroryza aristata.

Great white egrets Ardea alba in great numbers over Rio Nanay.

Rio Amazonas


This Pinecone Pleco Pseudorinelepis genibarbis was caught in the shallow waters (1 meter deep) of a 5 meter wide channel in Rio Amazonas.


The grass here is floating and that is a perfect adaptation to the changing water levels. We caught many fish under the massive floating islands. 



A special thanks to: 

Brian Sidlauskas (Anostomidae)

Robson Tamar da Costa Ramos (Achiridae)

Dan Olsen (web support)

Claus Christensen (Aquatic plants)

Nikolai Filskov (Aves)

Mark Henry Sabaj (Doradidae)

Henrik Bringsøe (Anura)

Best Regards Peter Petersen




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