Brazil Mato Grosso do Sul

Brazil, Mato Grosso do Sul

By Peter Petersen

Rio Sucuri

Near the city of Bonito a lot of clearwater rivers flow from underwater springs. These relatively small rivers are among the clearest I have encountered. This one is called Rio Sucuri which mean Anaconda.  

The undescribed Spring Water Bristlenose Pleco (Ancistrus sp. Rio Fomoso). This is a youngster just around 6 cm. This species seems to exist in all the spring water rivers which run into Rio Formoso system.

In this region a common aquatic plant is the Large Leaved Sword Plant (Echinodorus macrophyllus). We found some plants around 80-90 cm long. In my experince this is not so common in this species.

A pair of Two Spotted Pike Cichlids Saxatilia lepidota (Formerly Crenicichla lepidota) and South American Water Lily (Nymphaea gardneriana).

The under jaw of the South American tapir (Tapirus terrestris) also known as the Lowland tapir.

Large areas of this clearwater riversystem is covered in Brazilian Pennywort (Hydrocotyle leucocephala) and South American Water Lily (Nymphaea gardneriana). I found lots of fish fry hiding in these dense underwater plants. 

The Charophyte green algae (Chara fibrosa) is common in the crystal clear water of Rio Sucuri.

Charophyte green algae (Chara fibrosa), Shining pondweed (Potamogeton illinoensis) and Watermilfoil (Myriophyllum aquaticum).

The Dwarf Sword Plant (Helanthium bolivianus) with Piraputangas (Brycon hilarii) the Characin (Astyanax lacustris) in the background.

South American Water Lily (Nymphaea gardneriana) and Dwarf Sword Plant (Helanthium bolivianus).

Pantanal Pike characin (Acestrorhynchus pantaneiro) cruising around the Shining pondweed (Potamogeton illinoensis) looking for smaller fish to eat. They seem to prey mostly on smaller characins.

The Aimara (Hoplerythrinus unitaeniatus) is another predator in this river system. I often found them in smaller groups of up to 6-8 specimens hunting the characins (Astyanax lacustris).

South American Water Lily (Nymphaea gardneriana) and Shining pondweed (Potamogeton illinoensis).

The color of the South American Water Lilys (Nymphaea gardneriana) leaves change according to the amount of light it gets. Plants in direct sunlight usually have bright red submerged leaves like this photo above. The pigments (called anthocyanins) absorb radiation and convert it into heat energy, which benefits the plants. The South American Water Lilys (Nymphaea gardneriana) like many other plants, simply protect themselves from too much sunlight. 

A very young Basilisk Pleco (Hypostomus basilisko). This specimen is around 4-5 cm TL.

Gastropod shells are found is large quantities all over this river system. Most of them belong to the Apple snail (Pomacea canaliculata)


These gastropods are native to this area. They lay their eggs in aquatic plants above the water surface. The cluthes of eggs are bright pink and easy to spot. The Apple snail (Pomacea canaliculata) has gills and operculum. 

Rio Formoso

All the clearwater spring rivers run into Rio Formoso. But here the water is more cloudy. This undescribed Formoso Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2) only seem to occur in the murky waters.

This is a younger specimen of the undescribed Formoso Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2)

This is an adult female Formoso Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2) in stress colors. They are very shy and getting good photos demanded great patience.

The adult males of Formoso Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2) were usually guarding their caves. Always ready to make a quick escape into the hole.

The head of an adult male Formoso Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2).

The iron level in the river is high and in some areas the clay turn red as a result. Here the clay was hard and this Formoso Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2) found a cave formed by the current.

A semi-adult undescribed Formoso Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2) in the perfect light from a sunset.

An adult male of the undescribed Formoso Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2) hiding in a clay cave.

A juvenile of the undescribed Formoso Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2) in stress coloration. Hiding under a large tree trunk in the fast current.

Above is a semi adult of the Undescribed Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2) in stress colors as well.

A dorsal view of a female undescribed Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2) after capture.

The head of the female undescribed Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2). Notice the short odontodes.

View of the belly of the female undescribed Mainriver Bristlenose Pleco (Ancistrus sp. Rio Formoso 2)

The Characin (Astyanax lacustris) is a common fish in this river system. I noticed them preying on insect larvae and fish fry. But they also seem to eat detritus.

The Blue Shrimp Catfish (Imparfinis mirini) also known as (Imparfinis schubarti) hide under the rocks and roots during the day and around sunset they start preying on shrimps, insects and fish fry.

The Blue Shrimp Catfish (Imparfinis mirini) also known as (Imparfinis schubarti) is very sensitive. This is stress colors after capture. After a few shots it recovered and fled into hiding under a big log.

Two Spotted Pike Cichlid Saxatilia lepidota (Formerly Crenicichla lepidota) hiding under some branches. This specimen is around 15 cm TL.

Nature is not perfect. This Basilisk Pleco (Hypostomus basilisko) had some kind of eye defect. I guess this is why I could get this close with the camera without scaring it away.

A young 7 cm Basilisk Pleco (Hypostomus basilisko) resting in the silt covered clay close to the river bank. Their camouflage fits perfectly with both bottom, branches and rocks as they change their colors rapidly.

Larger specimens of the Basilisk Pleco (Hypostomus basilisko) usually hang out near caves like this 25 cm fish. The current and the plecos forms the caves in the soft clay bottom. 

This young Basilisk Pleco (Hypostomus basilisko) was hanging on to a flooded branch. When I grabbed it I noticed a least 5 to 6 others in same size on the same branch. The specimens I found on branches were all reddish.

This Redtail tetra (Aphyocharax dentatus) is around 7-8 cm TL. I often found one in shoals with other characins in simular sizes. But never more than one or two of this species in each shoal.

Another interesting species is the Formoso Pleco (Hypostomus froehlichi). This is a large species. We observed specimens more than 60 cm long. But small fish like this 11 cm young we only found in the small rivers.

A dorsal view of the Formoso Pleco (Hypostomus froehlichi).

The mouth of the Formoso Pleco (Hypostomus froehlichi)

I caught this little Formoso Pleco (Hypostomus froehlichi) here in this hard clay formation in very fast current.

Head of the Formoso Pleco (Hypostomus froehlichi).

Dorsal fin of the Formoso Pleco (Hypostomus froehlichi).

Tail of the Formoso Pleco (Hypostomus froehlichi).

The Formoso Pleco (Hypostomus froehlichi) with stress colors after capture.

The nostrils of the Formoso Pleco (Hypostomus froehlichi) are very large in small specimens.

The smallest specimens, like this 2 cm specimen, I usually found in waterfalls. 2-4 cm specimens of Formoso Pleco (Hypostomus froehlichi) have a very destinct pattern and colors.

They have slightly yellow to orange finns and the young Formoso Pleco (Hypostomus froehlichi) seem to prefer the shade but are diurnal. This is a 3 cm specimen.

Same 3 cm specimen of Formoso Pleco (Hypostomus froehlichi) from another angle. 

At around 5 cm the yellow and orange colors fade and the spots begin to appear on the young Formoso Plecos (Hypostomus froehlichi).

In the shallow waters larger specimens of the Formoso Pleco (Hypostomus froehlichi) looks greenish in color. This fish is around 30-35 cm.

The Formoso Pleco (Hypostomus froehlichi) is not that shy. I often got within 50 cm of them before they fled.

A young Paraguay Poptella Tetra (Poptella paraguayensis). This specimen is about 2-3 cm TL. Small shoals of these were swimming very close to the river bank.

The Paraguay Poptella Tetra (Poptella paraguayensis) seem to eat detritus and insect larvae.

I also found freshwater crabs belonging to the family Trichodactylidae. This might be Zilchiopsis oronensis or Sylviocarcinus australis but I only caught females so I cant really be sure.

I observed these freshwater crabs (Zilchiopsis oronensis or Sylviocarcinus australis) scavenging the river bottom for fallen fruits and dead fish. 

The apron of the female freshwater crabs (Zilchiopsis oronensis or Sylviocarcinus australis). As in other crabs the apron is wider in females and the males first gonopod is used for an accurat identification.

Close up I noticed the Threespot leporinus (Leporinus friderici) in this river system have red markings on the scales on the sides and dorsal region as well.

What seem to be the Common Woodcat (Trachelyopterus galeatus) is present in great numbers in some regions of this river system. I found them mostly in the fast flowing parts of the river.

I found the Common Woodcat (Trachelyopterus galeatus) normally under rocks and pebbles but also between the dense vegetation along the banks of the river. 

What seem to be the Green Dwarf Tetra (Hemigrammus tridens) feed on small particle of organic matter (Detritus). They seem to grow to a maximum of around 2 cm TL in this region. This is an adult specimen.

The Green Dwarf Tetra (Hemigrammus tridens) seem to prefer the shallow water (less than 60 cm deep) and usually in the shade. Its a very active fish with a high metabolism.

At first glance it might look like one species. But in fact this is the 5 species shoaling: Redeye tetra (Moenkhausia sp. aff. sanctaefilomenae), Characins (Astyanax lacustris), Green Dwarf Tetra (Hemigrammus tridens), Beautiful Tetra (Moenkhausia bonita), Green Tetra (Jupiaba acanthogaster). The bio diversity here is amazing.

The rocks in Rio Formoso are often hardened clay which are easy to breake. They often swallow roots and branches like this. 

A shoal of Striped Characin (Astyanax lineatus) just above a small waterfall. This fast species seem to prefer the fast flowing waters. I observed them feeding both on bottom dwelling insects and insects drifting in the surface.

The Paraguay Dwarf Sucker (Otocinclus bororo) is common in Rio Formoso. The are shoaling but sometimes I found only 2-3 together and other times they were more than 40 individuals in a group.  

The Paraguay Dwarf Sucker (Otocinclus bororo) seem to eat detritus of rocks, roots and branches.

The Paraguay Dwarf Sucker (Otocinclus bororo) seem to grow to maximum of 5 cm TL.

An adult Paraguay Dwarf Sucker (Otocinclus bororo) in the light from a sunset. This specimen is around 4 cm TL. 

The light is an important factor when photographing fish under water. In my experience sunlight is the best light source. Giving the most natural colors to the fish and the surroundings. Above a Paraguay Dwarf Sucker (Otocinclus bororo).

Paraguay Dwarf Sucker (Otocinclus bororo) on hardened clay.

The Southern Nose Tetra (Creagrutus meridionalis) is common in the shallow parts of the river. I usually found them shoaling with other characins of simular size. Its a fast species with a very distinct head shape. They seem to feed mainly on detritus.

This pike cichlid (Crenicichla vittata) was not shy. Every step I took stirred up som particles and these guys were always there to look for food items. Usually worms, water nymphs or small characins.

The colors of the pike cichlid (Crenicichla vittata) changes a lot depending on the mood and the gravel. Young fish usually had these light colors when hunting their prey.

This specimen of the pike cichlid (Crenicichla vittata) is around 18-20 cm TL.

A common characin here is the Paraguay darter (Characidium laterale). They occur in the whole river system. They seem to feed on detritus. Youngsters like these are schooling. 

As the the Paraguay darter (Characidium laterale) grows they seem to live more solitary lifes. They are very curious animals and will come quite close if you are still.

This is a fully grown Paraguay darter (Characidium laterale) female. They seem to reach around 7 cm.

This Two Spotted Pike Cichlid Saxatilia lepidota (Formerly Crenicichla lepidota) is a juvenile. This species seem to be the most common of the pikes in this region. 

Like other Pike Cichlids I have observed , the Two Spotted Pike Cichlid Saxatilia lepidota (Formerly Crenicichla lepidota) stay with their parents until they are sexually mature. which I havent seen in other cichlids.

Not something you see every day a Paraguay Twig Catfish (Farlowella paraguayensis) watching a live stream of Characins on the gopro.

Not exactly the best camouflage for the Paraguay Twig Catfish (Farlowella paraguayensis). The guys are excellent swimmers by the way. Very fast.  

The Redeye tetra (Moenkhausia sp. aff. sanctaefilomenae) is also a common fish here. The large schools are always deep in the vegetation. After closer study the specimens I found in these waters differs slightly from the very closely related species: Moenkhausia australis, Moenkhausia oligolepis and Moenkhausia forestii. by having 1 less transverse series of scales above the lateral line (4) vs 5 in Moenkhausia forestii. The distribution range does not seem to fit the species, which is why I leave it as Moenkhausia sp. aff. sanctaefilomenae at this point in time.

Redeye tetras (Moenkhausia sp. aff. sanctaefilomenae) are quite shy and prefer densely vegetated areas of the river. I swam in to the vegetation and stayed still for a while and they came close but still very nervous. This was sadly the the best photo I got. 

Rio da Prata

The Piraputanga (Brycon hilarii) is one of the most colorful fish of this region. They form schools of sometimes up to several hundred individuals. I only oberserved them eating fruits and seeds.


The Piraputangas (Brycon hilarii) live up to their genus name (Brycon = to bite). I observed males biting chunks of each others tail off. Possibly because of some kind of hierarchy within the shoal.

A field of Stargrass (Heteranthera zosterifolia) with Green Tetra (Jupiaba acanthogaster), Threespot leporinus (Leporinus friderici) and Jewel Tetras or Red Serpa (Hyphessobrycon eques).

The Streaked prochilod (Prochilodus lineatus) is the largest detrivore here and as the Jumbo Headstander (Megaleporinus obtusidens) it too is quite common in this river system.

 Streaked prochilod (Prochilodus lineatus) has a very destinct zig zag pattern in the scale rows.

A Streaked prochilod (Prochilodus lineatus) feeding. This specimen is around 45-50 cm TL.

Some of the Streaked prochilods (Prochilodus lineatus) had bite marks in their pelvic fins. I did not observe any territorial desputes between them so it might be a predator.

This may look like solid rock but actually this is very soft clay and the caves are formed partly by currents and partly by fish like plecos digging in the holes and forming their perfect spawning caves.

The Striped Leporinus (Leporinus striatus) in this river system have a clear red spot on the lips. I only observed them eating detritus and algae. 

Streaked prochilods (Prochilodus lineatus), Piraputangas (Brycon hilarii), Threespot leporinus (Leporinus friderici), Jewel Tetras or Red Serpa (Hyphessobrycon eques) in a meadow of Stargrass (Heteranthera zosterifolia)


Inspiration for aquarists. The plant in the background is the Dwarf Sword Plant (Helanthium tenellum). 

I found the Dwarf Sword Plant (Helanthium tenellum) very common here along the sandy river banks.

This is the habitat of the Jewel Tetra also known as the Red Serpa (Hyphessobrycon eques) and the aquatic plant Stargrass (Heteranthera zosterifolia) which is in the same family as the Water Hyacinth (Pontederiaceae).

Lucias Whiptail (Loricaria luciae) hiding in the sand. These are well camouflaged catfish which can grow larger than I expected. This one was 29 cm.

I only found the Lucias Whiptail (Loricaria luciae) in very shallow waters. From around 30 cm deep and up. 

As you can see in this video the Paraguay Twig Catfish (Farlowella paraguayensis) is an excellent swimmer and a master of camouflage.

With a river bottom like this. Full of leaves, branches, twigs, pieces of driftwood the fish have plenty of places to hide. This river system holds many interesting species still unknown to us.  

This Characin (Astyanax sp.) is simular to the Single Tooth Tetra (Astyanax marionae). Lacking the bright red marking in the upper caudal fin lobe. This specimen is 4-5 cm TL.

These clearwater spring rivers provides inspiration for aquascapers. This photo was taken right next to a small spring in the shallow waters of Rio da Prata. The plant here is the Dwarf Sword Plant (Helanthium bolivianus)

Some more inspiration for aquascaping. Piraputangas (Brycon hilarii), Characins (Astyanax lacustris) and Striped Leporinus (Leporinus striatus).

A video of the water snake (Helicops leopardinus) and the aquatic plant Stargrass (Heteranthera zosterifolia).

An adult of the undescribed Spring Water Bristlenose Pleco (Ancistrus sp. Rio Fomoso). This species is present in all the clearwater spring rivers which run into the Rio Formoso. But I never found them in the main river. 

The undescribed Spring Water Bristlenose Pleco (Ancistrus sp. Rio Fomoso) seem to prefer wood. I found them mostly on and in roots, branches and logs.

Dorsal view of undescribed Spring Water Bristlenose Pleco (Ancistrus sp. Rio Fomoso). 

This undescribed Spring Water Bristlenose Pleco (Ancistrus sp. Rio Fomoso) specimen is 9 cm long.

The mouth of the undescribed Spring Water Bristlenose Pleco (Ancistrus sp. Rio Fomoso)

A semi adult Two Spotted Pike Cichlid Saxatilia lepidota (Formerly Crenicichla lepidota) in a field of Stargrass (Heteranthera zosterifolia).

Piraputanga (Brycon hilarii) eating a fruit that hit the surface. With their powerfull bite they will crush the food items leaving small particles for the smaller characins.

The presence of mammals living in this river is clear. I found fresh tracks from the Lowland tapir (Tapirus terrestris), Lowland Paca (Cuniculus paca) and Capybara (Hydrochoerus hydrochaeris) and many bones.

Water flows from underwater springs making this river system extremely clear. The temperature in these springs vary a little. Most were around 24-27 degrees C.

The amount of water passing through these springs are incredible.  

A habitat photo with 3 common aquarium fish. The Jewel Tetra or Red Serpa (Hyphessobrycon eques), Redeye tetra (Moenkhausia sp. aff. sanctaefilomenae) and the Dimerus cichlid (Cichlasoma dimerus). The plant here is the Dwarf Sword Plant (Helanthium bolivianus)

A video of a snakebird (Anhinga anhinga) swimming underwater in between the branches. This predator bird feeds on most fish in this river system.

Amoung the branches and leaves in the bottom we found lots of fish fry from cichlids, characins and catfish.

Larger Basilisk Plecos (Hypostomus basilisko) seem to be more active during sunset and sunrise. This 30 cm fish was hiding in the shade of a large piece of driftwood.

I often found larger Basilisk Plecos (Hypostomus basilisko) in the shade under the river bank. I noticed some of them were digging breeding caves in the soft clay.

This Basilisk Pleco (Hypostomus basilisko) is trying to escape. Slow movements are crucial when you observe these beautiful creatures.  

The Striped Leporellus (Leporellus vittatus) seem to prefer the fast flowing parts of the river especially around waterfalls. Its a fast species. I often found them shoaling with Scrapetooths (Parodontidae).

In some parts of the river the current sorts the sand and gravel. This almost looks like gravel used for aquariums. 

Jumbo Headstander (Megaleporinus obtusidens) is the largest anostomid in the world. Here eating detritus and algae. I also observed them eating moss. The largest specimens I saw were around 40-50 cm TL.

The largest specimens of the Threespot leporinus (Leporinus friderici) I came accross was about 35-40 cm TL. They were often shoaling with Jumbo Headstanders (Megaleporinus obtusidens).

The Jumbo Headstander (Megaleporinus obtusidens) often swam in small shoals here nipping to some Stargrass (Heteranthera zosterifolia). They did not seem to eat the leaves but only the algae growing there. 

A Jumbo Headstander (Megaleporinus obtusidens) filtrating the gravel for detritus. Sand and small pebbles are being recircled through the gills.

The mouth of the Jumbo Headstander (Megaleporinus obtusidens) reminds me a lot of Flannel-mouth characiforms (Prochilodontidae) genera Prochilodus and Semaprochilodus.

Jumbo Headstander (Megaleporinus obtusidens) and the aquatic plant Stargrass (Heteranthera zosterifolia) is a beautiful scenery.

This pair of Jumbo Headstander (Megaleporinus obtusidens) was grassing algae of the Stargrass (Heteranthera zosterifolia).

This male Two Spotted Pike Cichlid Saxatilia lepidota (Formerly Crenicichla lepidota) is in full breeding colors. He is around 15 cm TL and he was trying to chase the other male away (His reflection in the camera lense).

The Nose Scrapetooth (Parodon nasus) was difficult for me to photograph. This species is fast and seem to prefer the fast flowing waters around waterfalls. Often shoaling with other closely related species.

Fully grown the Nose Scrapetooth (Parodon nasus) seem to change color and pattern. This fish is around 18-20 cm TL.

Habitat of the Paraguay Twig Catfish (Farlowella paraguayensis) and juvenile Basilisk Plecos (Hypostomus basilisko).

I measured the pH value in this river system and it was between 7.3 and 7.5 in all samples. The aquatic plant Stargrass (Heteranthera zosterifolia) covered large areas of the bottom.

The Striped Leporellus (Leporellus vittatus) here on a background of the aquatic plant Stargrass (Heteranthera zosterifolia) and volcanic rocks. Natures perfect aquascape!

A video of Cuvier's dwarf caiman (Paleosuchus palpebrosus) a peacefull species which avoid human contact. This species is as important part of the eco system.

Basilisk Pleco (Hypostomus basilisko) near the entrance to a soft clay cave. Adults in breeding coloration have almost no pattern left. They are usually brown or maroon with silvery eyes.

This Dorado (Salminus brasiliensis) was around 70 cm TL. It was hunting small characins (Astyanax lacustris) at high speed.

The Green Tetra (Jupiaba acanthogaster) are present in large schools. This species seem to reach around 5-6 cm TL. The seem to prefer the spring rivers.

The Green Tetra (Jupiaba acanthogaster) might be small but it has a powerfull bite. This one found one of my mosquito scratch wounds and kept tearing off skin. The connection to the piranha is noticeable. Ouch! Reverse sushi ;)

When the Basilisk Plecos (Hypostomus basilisko) hides, they change their color and are perfectly camouflaged within seconds. They trust their ability to disappear so much that they stay still and you can get very close before they flee.

The pike cichlid (Crenicichla vittata) can grow larger than I thought. This specimen is around 40-45 cm TL. Notice the small fry around him. The male and female seem to take care of their your until they are around 8-10 cm TL.

The female pike cichlid (Crenicichla vittata) usually stay closer to the fry than the male. I estimate this pair had around 500 fry swimming around them.  

Above is a hyperlapse of a Rio da Prata underwater experience.

Piraputangas (Brycon hilarii) and Threespot leporinus (Leporinus friderici) shoaling under the forest trees catching the fruits that fall to the surface. These fish are known as important seed scatterers.

Clear spring water, volcanic rocks, sand and Stargrass (Heteranthera zosterifolia) almost make this look like an aquarium.

Large specimens of the Formoso Pleco (Hypostomus froehlichi) usually inhabits the larger part of the rivers. This 60 cm fish I found on the rock shelfs 2 meters down.

But its not uncommon to find the Formoso Pleco (Hypostomus froehlichi) in 10 meters depth. 

A video of Formoso Pleco (Hypostomus froehlichi), Threespot leporinus (Leporinus friderici), Green Tetra (Jupiaba acanthogaster) and Piraputangas (Brycon hilarii).

Semiadult 35-40 cm Formoso Pleco (Hypostomus froehlichi) with Threespot leporinus (Leporinus friderici) and Piraputangas (Brycon hilarii) in the background.

Rasp marks from the Formoso Pleco (Hypostomus froehlichi). They seem eat only detritus. 

The Formoso Plecos (Hypostomus froehlichi) on the rocky shelfs were not shy at all. They moved when I got within about 50 cm from them. Males like this seem to have larger spines on their pectoral fins.

Feces from the Formoso Pleco (Hypostomus froehlichi) are all over the rocky shelfs and reveals large quantities of this catfish species. 

Some Formoso Plecos (Hypostomus froehlichi) had damaged fins properly from Piraputanga (Brycon hilarii) bites.

This is a 35-40 cm Formoso Pleco (Hypostomus froehlichi).

The color pattern of the Formoso Plecos (Hypostomus froehlichi) varies but they all seem to have rings. The pattern is simular to those of the genus Pterygoplichthys even though its clearly i Hypostomus species.

Formoso Plecos (Hypostomus froehlichi) resting on the rocky shelfs of the river bank down to about 10 meters. Threespot leporinus (Leporinus friderici) and Piraputanga (Brycon hilarii) normally stays from 5 meters and up. 

Two Spotted Pike Cichlid Saxatilia lepidota (Formerly Crenicichla lepidota) ready to breed. This fish is around 12 cm TL.

Pure inspiration for aquascaping.  The aquatic plants here are: Stargrass (Heteranthera zosterifolia) and Brazilian moss (Vesicularia dubyana). The ancient volcanic rock is formed from lava erupted from underground activities.

The Brazilian moss (Vesicularia dubyana) in its native environment. I noticed several small characin species breeding in this pad of moss. 

The proficient Zookeeper Simon Boye Nielsen camouflaged in algae. This slowmoving part of the river housed many interesting small characins. They hide in the shade of the floating algae.

A shoal of Jewel Tetra also known as the Red Serpa (Hyphessobrycon eques) in the shallow water under the floating algae.

The bottom in this river varies a lot. Fast flowing parts of the river normally consists of sand, gravel, pebbles and soft clay like in the photo above.

Streaked prochilod (Prochilodus lineatus) in breeding condition have yellow anal, pelvic and pectoral fins. These fish are around 60 cm TL.

Rio Baía Bonita

Another clearwater spring river is Rio Baía Bonita. This runs into the Rio Formoso as well. The amounts of aquatic plants species and the quantity of plants here are amazing.

Males of the Beautiful Tetra (Moenkhausia bonita) in breeding condition. I only observed them eating insect larvae and detritus. They seem to grow to a maximum lenght of around 4-5 cm TL. 

The tail of Beautiful Tetras (Moenkhausia bonita) can turn almost completely black with only the white tips visible (in males). Notice the dorsal and anal fin is longer than in the females (female in the background).

The Two Spotted Pike Cichlid Saxatilia lepidota (Formerly Crenicichla lepidota) prey on small characins, shrimps and nymphs. The color variation in this species is amazing and the color change is rapid depending on their moods. This color is used for foraging. 

This beautiful undescribed green characin (Bryconops sp. cf. melanurus) is common in the Rio Formoso river system. They seem to grow to a length of around 10 cm TL. I observed them feeding on insect larvae and detritus. This photo is taken in Rio Baia Bonita. The plant is Guppy Grass (Najas guadalupensis).

The undescribed green characin (Bryconops sp. cf. melanurus) is a very active species. They normally swim in smaller groups often shoaling with other species of characins.

This Green characin (Bryconops sp. cf. melanurus) had a damaged caudal fin. I only found this species in the shallow waters usually from 1 meter and up. They seem to prefer the densely vegetated parts of the rivers.

The top predator in this river system is the Dorado (Salminus brasiliensis). They often hide in schools of other fish like these Streaked prochilods (Prochilodus lineatus).

The diversity of plants in the clearwater spring rivers are amazing. This is Watermilfoil (Myriophyllum aquaticum), Guppy Grass (Najas guadalupensis) and Shining pondweed (Potamogeton illinoensis).

The Blackline Toothless Characin (Steindachnerina brevipinna) is common in this riversystem. Its a fast and shy species which seem to feed on detritus mainly. Largest specimens I encountered was around 12 cm TL.

Large shoal of Streaked Prochilods (Prochilodus lineatus) in a field of Guppy Grass (Najas guadalupensis) with Water Snowballs (Gymnocoronis spilanthoides).

A school of the Green Tetra (Jupiaba acanthogaster) in Guppy Grass (Najas guadalupensis), Water Snowballs (Gymnocoronis spilanthoides), Large Leaved Sword Plant (Echinodorus macrophyllus) and the Charophyte green algae (Chara rusbyana).


The schools of Green Tetra (Jupiaba acanthogaster) can sometimes count several thousands individuals often hiding in the dense vegetation.

Green Tetra (Jupiaba acanthogaster) in Guppy Grass (Najas guadalupensis), Large Leaved Sword Plant (Echinodorus macrophyllus) and the Charophyte green algae (Chara rusbyana).

The water parameters from the water test I sampled in this river system I sent to the German laboratory ATI:

Parameter  Rio Baía Bonita Rio Formoso  Unit  Description
pH 7.3 7.5  pH Acidic/basic
KH 12.61 11.98  °dKH  Carbonate hardness
Salinity 0.03 0.01   PSU Salinity
Cl 12.72  0.00 mg/l Chlorine
NA 10.94 3.94  mg/l Sodium (Natrium)
Mg 16.06  16.61 mg/l Magnesium
0.00  0.00 mg/l  Sulfur
Ca   80.77 67.73  mg/l  Calcium
 K  1.79 0.72  mg/l Potassium (Kalium)
 Br  0.00 0.00  mg/l Bromine 
Sr  0.31 0.29  mg/l Strontium
0.01 0.00  mg/l  Boron
0.24 0.26  mg/l Fluorine 
 Li 0.00   0.00 μg/l  Lithium
Si  5433  4712 μg/l  Silicon
 I 0.00  0.00 μg/l  Iodine
 Ba 24.00 21.43  μg/l  Barium
Mo 1.26 1.08  μg/l Molybdenum
 Ni 0.00  0.00 μg/l  Nickel
Mn  0.00  0.00 μg/l  Manganese
As   0.0 0.00  μg/l  Arsenic
 Be 0.00  0.00 μg/l  Beryllium
Cr 0.0  0.00 μg/l Chromium
Co 0.00 0.00  μg/l Cobalt
Fe 0.00  0.00 μg/l Iron
Cu   5.32 11.66  μg/l Copper 
Se 0.00 0.00  μg/l Selenium
Ag 0.00 0.00  μg/l Silver
V 0.00  0.00 μg/l Vanadium
Zn 10.82 5.48  μg/l Zinc
Sn   8.78 22.58  μg/l  Tin
NO3 0.52 1.67  mg/l Nitrate
P 0.00  7.74 μg/l Phosphorus
PO4 0.00   0.02 mg/l Phosphate
Al 0.00 0.00  μg/l Aluminium
Sb 0.0 0.00  μg/l Antimony
Bi 0.00  0.00 μg/l Bismuth
Pb 0.00 0.00  μg/l Lead
Cd 0.00  0.00 μg/l Cadmium
La 0.00  0.00 μg/l Lanthanum
Tl 0.00  0.00 μg/l Thallium
Ti 0.00   0.00 μg/l Titanium
W 0.00  0.00 μg/l Tungsten (Wolfram)
Hg 0.00 0.00  μg/l Mercury


The plants here are: Shining pondweed (Potamogeton illinoensis), Guppy Grass (Najas guadalupensis) and Large Leaved Sword Plant (Echinodorus macrophyllus).


A special thanks to:

Luiz Tencatt (Siluriformes)

Steven Grant (Siluriformes)

Pete Liptrot (Cichlidae)

Fernando Carvalho (Characiformes)

Flávio Lima (Characiformes)

Willem Heijns (Cichlidae; Heroines)

Brian Sidlauskas (Networking)

Oliver Lucanus (Anostomidae) Below Water

Celio Magalhaes Filho (Trichodactylidae)

Dan Olsen (Web Support)

Claus Christensen (Aquatic plants)


Rio Xingú

Wildlife in and around the river system

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Costa Rica

Birds, lizards, frogs, freshwater fish, rainforest and dry forest



Ladybird spider (Photo article coming soon)



Amager Fælled a nature hot spot in Copenhagen, Denmark

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