Amazon oxbow lake biotope aquarium, a freshwater habitat in Peru
Peruvian Amazon river
Aerial view of a meandering river in the rainforest of Peru. If you look closely, two oxbow lakes are visible towards the center of the image. One is considerably "darker" than the other, but both are isolated from the main channel of the river.
BIOTOPE AQUARIA
A biotope aquarium is set-up to simulate a natural habitat. The fish, plants, water chemistry, light conditions, and tank furnishings are similar to those that can be found in a specific natural setting.
OXBOW LAKE IN SOUTHWESTERN PERU
The southeastern part of Peru is arguably the most biodiverse place on the planet. This biological wealth extends to the river systems found in this tropical rainforest environment.
This biotope profile will look specifically at two oxbow lakes found along the Madre de Dios and Tambopata rivers in the Madre de Dios river system upstream of Puerto Maldonado.
Oxbow Lakes
Virtually all lakes in this part of the Amazon are oxbow lakes. An oxbow lake is a crescent-shaped lake formed when a river changes course. In lowland Amazonia where soft alluvial soils dominate, meandering rivers gradually shift due to erosion and sediment deposition. Oxbow lakes typically form when loops in the river become so extreme that the main channel erodes a new straighter route, leaving the river bend apart from the river. As time passes, the oxbow lake becomes increasingly distant from the main channel. Water conditions change as the water stagnates.
The characteristics of an oxbow lake generally depends on its age. Younger oxbow lakes may be "flushed" by river currents, especially during the flood season. These lakes tend to be slightly more turbid (less transparent) and less acidic than older lakes more distant from the river channel.
Oxbow Lake Characteristics
Depth: Oxbow lakes generally range in depth from 16 feet (5 meters) during floods to less than 6 feet (2 m) at low water.
Thermal stratification: Oxygen and temperature tend to decrease with depth in lakes due to thermal stratification whereby cooler waters do not mix with warmer waters. Thermal stratification is more common in older, more isolated oxbow lakes.
Temperature: According to Amazon Headwaters, a book on the rivers of southeastern Peru, the average temperature of oxbow lakes is 76-80 degrees Fahrenheit (24.6-26.6 degrees Celsius). Oxbow lakes are generally warmer than nearby river channels and shaded forest streams. Temperature rises during the low water period.
Water chemistry: According to Amazon Headwaters, the pH of oxbow lakes ranges from 5.4-6.8 while conductivity is 40-68. pH and conductivity rise during the low water period, possibly due to "increased phytoplankton production." Water transparency also increases at this time.
Substrate: The substrate consists of mud with overlaying organic matter and vegetation in varying states of decomposition. There is a fair amount of submerged wood.
Other wildlife: Both oxbow lakes are inhabited by families of giant river otters. Giant river otters are the top predators in these ecosystems, feeding on 5-10 kg of fish per day. Other non-fish predators of resident fish are primarily birds. Tambopata (650 species) and Manu (1000 species) are incredibly rich with bird life.
Aquatic Plants
Underwater shot of Bladderwort (top) and Victoria cruziana (bottom)
Bladderwort, Utricularia foliosa is especially abundant in this habitat.
Oxbow lakes in this region have considerable aquatic plant growth. Most conspicuous are free-floating plants including Eichhornia, Pistia, Salvinia, Victoria cruziana, and Bladderwort (Utricularia foliosa), which grows densely and extensively in the lakes. Amazon sword plants (Echinodorus sp.), Vallisneria, Panicum, and Hymenachne were also present, though in lesser numbers. According to Amazon Headwaters, there are about 35 species of "aquatic herbs and shrubs that are characteristic of floodplain lakes of the rio Madre de Dios lowlands."
Surrounding vegetation: The oxbow lake is surrounded by reeds. There are thick floating plants where the lake narrows.
Tank setup
Tank size will depend on the type of fish you plan to keep in your biotope aquarium. If you are going with smaller tetras, catfish, and Apistogramma then you can use a smaller tank than if you plan to go with larger cichlids and characins.
Current: Direct filter outflows to minimize current. Oxbow lakes are quite still.
Lighting: Bright overhead lighting. You can moderate lighting with some floating plants if desired.
Layout: Dense planting along the sides and rear of the tank with open swimming areas. Wood can be used as well.
Substrate: Fine gravel or sand is acceptable since you probably don't want to use decaying leaf matter and mud which is naturally found in this biotope.
Other notes: You might consider using some peat moss in your filtration system to reduce the pH and soften the water. Peat moss can also mimic the slightly tea-colored water conditions that result from the inflow of blackwater streams.
Fish suitable for aquariums
The rio Madre de Dios probably has more than 600 species, many of which have yet to be described according to Amazon Headwaters. Detritus-feeders, invertebrate-feeders, and seed- and fruit-eating species are abundant in the system.
The aquarium fisheries trade began in the department of Madre de Dios in 2002 according to Amazon Headwaters. The book says the rio Madre de Dios headwaters regions has advantages when compared with aquarium trade fisheries in other parts of the Amazon, namely that the seasonal high water period is "neither too deep nor too long to prevent aquarium trade fisherman from working during the rainy season. Elsewhere in the Amazon Basin aquarium trade fisheries largely stop during the flooding season." Further, the rio Madre de Dios watershed had a large number of endemic species, some of which are small and decorative enough to be attractive as aquarium fish. The book lists the following genera as promising for the aquarium trade: Abramites, Corydoras, Pterolebias, Apistogramma , Crenicichla, Mesonatua, Carnegiella, Gymnocorymbus, Hemigrammus, Tyttocharax, Tyttobrycon, Pyrrhulina, Ancistrus, Hypostomus, Pimelodella, and Pimelodus.
The following fish were observed by boat in the oxbow lakes of the rio Madre de Dios (near Manu National Park) and the rio Tambopata (Tres Chimbadas lake):
Mesonauta festivum was the most obviously abundant fish as viewed from the boat. Bloodfins and Moenkhausia were also common. Hatchetfish were found near reeds along the shoreline, while a stingray was seen partially buried in a muddy beach area.
FRESHWATER FISHES OF THE TAMBOPATA NATIONAL RESERVE
Compiled by Mario Napravnik
CHARACIDAE (72)
Acestrocephalus boehlkei
Acestrorrhynchus lacustris
Cachoro, Pike characin
Aphyocharax pusillus
Bloodfin
Aphyocharax alburnus
Bloodfin
Aphyocheirodon sp
Astyanaclnus multidens
Aslyanax abramis
Astyanax anteroides
Aslyanax bimaculatus
Astyanax fasciatus
Two spotted Astianax Silvery tetra
Astyanax maxiumus
Bario steindachneri
Blotch tailed bario
Brachichalcinus copei
Brycon erythropterum
Sabalo cola roja
Bryconacydnus ellisi
Bryconamencus pachacuti
Bryconops melanurus
Tail light tetra
Characidium fasciatus
Charax gibbosus
Glass Headstander
Charax tectifer
Glass Headstander
Cheirodon fugitiva
Cheirodon piaba
Cheirodon ait. notomelas
Creagrutus affinis
Creagrutus anary
Creagrutus beni
Ctenobrycon hauxwellianus
Galeocharax gulo
Gephyrocharax sp
Gymnocorymbus temetzi
Black widow, Skirt Tetra
Gymnocorymbus thayeri
Hemibrycon jelskii
Hemibrycon jabonero
Hemigrammus lunatus
Hemigrammus ocellifer
Head and tail light tetra
Hemmigrammus sp
Holoshestes heterodon
Hydroyicus sconberoides
Hyphessobrycon agulha
Red tailed flag tetra
Hysteronotus sp
Knodus aff. beta
Knodus gamma
Knodus megalops
Knodus aff. moenkhausii
Knodus smitthii
Knodus sp
Leptagoniates aff. pi
Moenkhausia barbouri
Moenkhausia comma
Moenkhausia dichroura
Spot tailed Moenkhausia
Moenkhausia jamesii
Moenkhausia oligolepis
Glass tetra
Moralesia tectifera
Myleus rubripinnis
Othonocheirodus lethostigmus
Paragoniates alburnus
Phenacogaster pectinatus
Piabina beni
Piaractus brachyponus
Pacu
Pigocentrus nattereri
Red piranha
Poptella compresa
Prionobrama filigera
Glass bloodfin
Raphiodon vulpinus
Chambira
Rhynobrycon negrensis
Roeboides affinis
Glass characin
Roeboides myersii
Glass characin
Salminus aflinis
Serrasalmus humeralis
Piranha
Serrasalmus rhombeus
Black piranha, Spotted piranha
Serrasalmus spilopleura
Fire mouth piranha
Tetragonopterus argenteus
Triportheus albus
Sardina, sapanama
Triportheus angulatus
Sardina, Narrow Hatchetfish, sapanama
Tyttocharax sp
Bristly mouthed tetra
GASTEROPELECIDAE (3)
Hatchet fish
Carnegiella schereri
Hatchet lish
Carnegiella myersii
Myersi hatchetfish
Thoracocharax stellatus
Silver hatchetfish
ERYTHRINIDAE (3)
Trahlras, huasacos
Erythrynus eryihrinus
Short finned trahira
Hoplerytrhinus unitaeniatus
Trahiras, huasacos
Hoplias malabaricus
Fasaco, Tiger fish, trahira
LEBIASINIDAE (1)
Pyrrhulina
Pyrrhulina vittata
Banded pyrrhulina
PROCHILODONTIDAE(2)
Prochilodus mariae
Prochilodus nigricans
CURIMATIDAE (5)
Curimata sp
Cyphocharax sp
Steindachnerina dobula
Steindachnerina guentheri
Steindachnerina hypostoma
ANOSTOMIDAE (3)
Leporinus
Leporinus friderici
Friderici leporinus
Leporinus striatus
Striped leporinus
Leporinus yophoru
GYMNOTIDAE (2)
Knife fish
Gymnotus carapo
Banded Knife fish
Gymnotus coatesi
Knife fish
STERNOPYGIDAE (2)
Knife fish
Stemopygus macrurus
Ghost Knife fish
Sternopygus virescens
Knife fish
HYPOPOMIDAE (2)
Knife fish
Hypopomus muelleri
Knife fish
Hypopomus sp
Spoted knife fish
ELECTROOPHORIDAE (1)
Electric eel
Electrophous electricus
Electric eel
RHAMPHICHTHYIDAE (1)
Gymnorhamphichthys sp
POTAMOTRIGONIDAE (1)
Potamotrygon motoro
Freshwater Stingray
ENGRAULIDAE (3)
Anchoviella carrikeri
Anchoviella guianensis
Lycengraulis batessi
ASTROBLEPIDAE (1)
Astroblepus sp
RIVULIDAE (1)
Rivulus urophtalmos
SCIAENIDAE (1)
Pachyurus schomburgkii
Amazon croaker
SYNBRANCHIDAE (1)
Synbranchus marmoratus
Atinga, Marbled Eel
CICHLIDAE (9)
Aequidens tetramerus
Saddle Cichlid
Apistogramma luelingi
Apistogramma urteagai
Bujurquina cordemadi
Bujurquina tambopatae
Tambopata Flag Cichlid
Cichlasoma boliviense
Crenicichla semicincta
Pike Cichlid
Mesonauta festivum
Festive Cichlid
Satanoperca jurupari
Jurupari, Eartheater, Demon eartheater
DORADIDAE (1)
Talking catfishes
Trachydora nattereri
Talking catfish
AUCHENIPTERIDAE(2)
Driftwood catfishes
Auchenipterus nuchalis
Trachelyopterus sp
ASPREDINIDAE (1)
Banjo catfish
Dysichtys sp
Smooth banjo catfish
PIMELODIDAE (15)
Antenna catfishes
Brachypatystoma sp
Zungaro, Gilded catfish
Brachypatystoma filamentosum
Salton, Gilded catfish
Brachypatystoma flavicans
Dorado, Gilded catfish
Cheirocerus eques
Goslinea platinema
Mota flemosa
Heptapterus sp
Impartinnis sp
Hanhortiamdia sp
Megalonema sp
Microglanis sp
Bumble bee cat
Pimelodella gracilis
Slender pimelodella
Pimelodella lateristriga
Pimelodus maculatus
Cunshi
Pimelodus ornatus
Pimelodella angelica
Pimelodus pictus
Pseudoplatystoma fasciatum
Doncella, Shovelnosed catfish
Rhamdia quelen
Rhamdia sebae
Zungaro zungaro
Zungaro
CETOPCIDAE (1)
Pseudocetopsis plumbeus
Whale catfish
TRICHOMYCTERIDAE (4)
Parasitic catfishes, Pencil catfish
Branchioica sp
Trichomycterus vittatus
Trichomycterus sp
Vandellia plazaii
Candiru
HELOGENIDAE (1)
Helogenes marmoratus
Marbled catfish
CALLICHTHYIDAE (4)
Armored Catfish, Corydoras
Callichthys callichthys
Shirui, Slender Armored Catfish
Corydoras semiaquilus
Coridora, Sharp nosed corydora
Corydoras stenocephalus
Coridora, cory
Hoplosternum thoracathum
Shirui, Port hoplo, Atipa
LORICARIIDAE (13)
Suckermouth catfish
Ancistrus leucostictus
Bristle nose
Ancistrus sp
Bristle nose
Aphianatorulus frankei
Chaetostoma sp
Farlowella sp
Hemiodontichthys acipenserinus
Farlowella sp.
Hypoptoma gulare
Hypostomus sp
Plecostomus, Sucker catfish
Rineloricaria morrowi
Whiptail catfish
Rineloricaria sp
Whiptail catfish
Otocinclus vestitus
Dwarf sucker catfish
Otocinclus sp
Sucker catfish
Sturisoma nigrirostrum
FRESHWATER FISH AVAILABLE FROM PUERTO MALDONADO, PERU DISTRIBUTOR Aquarium Gone Wild Peru lists the following fish as being locally available in the Madre de Dios region.
