Crenuchidae
Grajau Darter
Characidium grajahuense
FISH SPECIES
Freshwater Fish
Freshwater fish spend all or part of their lives in rivers, lakes, streams and wetlands. The label describes an environment, not one branch of the fish family tree, so freshwater species include many unrelated shapes and lineages.
FISH ATLAS / FIELD GUIDEFreshwater FishIN THIS CHAPTER01 / Characteristics02 / Lifestyle03 / Species04 / Field notes
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01 / NATURAL HISTORY
Characteristics
Freshwater habitats contain far less salt than seawater and can change quickly with seasons, floods and drought. Fish living there use many different strategies, from streamlined bodies for current to barbels that help find food near the bottom.
- 01River fish
- 02Lake fish
- 03Stream fish
02 / LIFESTYLE
Lifestyle
Life in freshwater follows the movement of water and food. Some fish hold position in a current and intercept drifting prey; others search plants or sediment for a meal. Changes in flow and water level can open feeding grounds or trigger movements toward spawning areas. These behaviors reflect how fish balance hydrodynamic energy expenditure against food intake.
OBSERVATION INDEX
- Holding position in a current
- Feeding among plants or sediment
- Movement with changing water levels
03 / SPECIES
Representative species
Discover representative species illustrating the ecological diversity, morphologies and adaptations of this group.
Grajau Darter
Doradidae
Granulated catfish
Pterodoras granulosus
Acestrorhamphidae
Grapefruit Jupiaba
Jupiaba anteroides
Distichodontidae
Grass-eater
Distichodus rostratus
Distichodontidae
Grass-eaters
Ichthyborus monodi
Cyprinidae
Gravel chub
Erimystax x-punctatus
Salmonidae
Gravenche
Coregonus hiemalis
Polypteridae
Gray bichir
Polypterus senegalus
Cichlidae
Gray Blue Pike Cichlid
Crenicichla tapii
Callichthyidae
Gray corydoras
Corydoras griseus
Nemacheilidae
Gray loach
Triplophysa dorsalis
Catostomidae
Gray Redhorse
Moxostoma congestum
Potamotrygonidae
Great freshwater stingray
Potamotrygon rex
Galaxiidae
Great Lake Galaxias
Paragalaxias eleotroides
Channidae
Great snakehead
Channa marulius
Catostomidae
Greater Jumprock
Moxostoma lachneri
Catostomidae
Greater redhorse
Moxostoma valenciennesi
Cyprinidae
Greater scissortail
Rasbora caudimaculata
Loricariidae
Greedo Fish
Peckoltia greedoi
Cyprinidae
Greek Rudd
Scardinius graecus
Cyprinidae
Greek Stone Gudgeon
Romanogobio banarescui
Cyprinidae
Greek stone gudgeon
Romanogobio elimeius
Balitoridae
Green Borneo sucker
Gastromyzon lepidogaster
Bryconidae
Green Brycon
Brycon orthotaenia
04 / FIELD NOTES
A closer look
What makes a fish freshwater?
It is recorded from inland waters with low salinity for all or part of its life cycle.
Are all freshwater fish closely related?
No. Freshwater is a habitat category that includes many separate evolutionary groups.
Can freshwater fish survive in seawater?
Most cannot; without physiological adaptations to excrete excess salt, their cells rapidly lose water through osmosis and dehydrate in hypertonic seawater.