Callionymidae
Freshwater Dragonet
Tonlesapia tsukawakii
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.
Freshwater Dragonet
Sciaenidae
freshwater drum
Aplodinotus grunniens
Cyprinidae
Freshwater minnow
Zacco platypus
Dorosomatidae
Freshwater sardinella
Sardinella tawilis
Cynoglossidae
Freshwater tongue sole
Cynoglossus heterolepis
Ehiravidae
freshwater tyulka
Clupeonella tscharchalensis
Poeciliidae
Fria toothcarp
Pseudopoecilia fria
Percidae
Fringed darter
Etheostoma crossopterum
Cyprinidae
Fringed-lipped Peninsula Carp
Labeo fimbriatus
Cyprinidae
Fuelleborn's Labeo
Labeo fuelleborni
Cichlidae
Fuelleborn's mouthbrooder
Haplochromis fuelleborni
Mochokidae
Fuelleborn's squeaker
Synodontis fuelleborni
Callichthyidae
Fuller's cory
Corydoras fulleri
Cichlidae
Fuscotaeniatus
Nimbochromis fuscotaeniatus
Alestidae
Gabon Tetra
Brachypetersius gabonensis
Galaxiidae
Galaxias
Galaxias globiceps
Galaxiidae
Galaxias
Galaxias neocaledonicus
Loricariidae
Galaxy Plecostomus
Leporacanthicus galaxias
Cyprinidae
Galaxy rasbora
Danio margaritatus
Cyprinidae
Gamtoos redfin
Pseudobarbus swartzi
Anabantidae
Gangetic koi
Anabas cobojius
Botiidae
Gangetic loach
Botia rostrata
Bagridae
Gangetic mystus
Mystus albolineatus
Ctenoluciidae
Gar characin
Ctenolucius hujeta
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.