Tetraodontidae
Amazon puffer
Colomesus asellus
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.
Amazon puffer
Loricariidae
Amazon sailfin catfish
Pterygoplichthys pardalis
Loricariidae
Amazon Twig Catfish
Farlowella amazonum
Belonidae
Amazonian Needlefish
Pseudotylosurus angusticeps
Cichlidae
Amazonian Pike Cichlid
Crenicichla sedentaria
Synbranchidae
Amazonian Swamp Eel
Synbranchus madeirae
Percidae
Amber darter
Percina antesella
Doradidae
Amblydoras hancockii
Platydoras hancockii
Ehiravidae
Amboaboa round herring
Sauvagella robusta
Anguillidae
American eel
Anguilla rostrata
Acestrorhamphidae
American Glassy Tetra
Hyphessobrycon eschwartzae
Polyodontidae
American paddlefish
Polyodon spathula
Nothobranchiidae
Amiet's Lyretail
Fundulopanchax amieti
Poeciliidae
Amistad gambusia
Gambusia amistadensis
Percidae
Ammersee Ruffe
Gymnocephalus ambriaelacus
Salmonidae
Ammersee saibling
Salvelinus evasus
Nemacheilidae
Amu-Darya stone loach
Nemacheilus oxianus
Siluridae
Amur catfish
Silurus asotus
Gobiidae
Amur goby
Rhinogobius similis
Salmonidae
Amur grayling
Thymallus grubii
Cyprinidae
Amur ide
Leuciscus waleckii
Gobionidae
Amur longnose gudgeon
Microphysogobio amurensis
Cyprinidae
Amur minnow
Rhynchocypris lagowskii
Esocidae
Amur pike
Esox reichertii
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.