Anguillidae
European eel
Anguilla anguilla
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.
European eel
Umbridae
European mudminnow
Umbra krameri
Elassomatidae
Everglades pygmy sunfish
Elassoma evergladei
Adrianichthyidae
Evers' ricefish
Oryzias eversi
Cyprinidae
Evrotas chub
Squalius keadicus
Cyprinidae
Evrotas minnow
Pelasgus laconicus
Cyprinidae
Ewaso Nyiro barb
Enteromius mimus
Cyprinidae
Ewaso Nyiro Labeo
Labeo percivali
Cyprinidae
Exclamation Barb
Dawkinsia exclamatio
Melanotaeniidae
Exquisite rainbowfish
Melanotaenia exquisita
Cyprinidae
Eyeless golden-line fish
Sinocyclocheilus anophthalmus
Osphronemidae
Eyespot Betta
Betta ocellata
Anabantidae
Eyespot ctenopoma
Ctenopoma ocellatum
Osphronemidae
Eyespot gourami
Parasphaerichthys ocellatus
Tetraodontidae
Eyespot pufferfish
Dichotomyctere ocellatus
Cyprinidae
Eyespot rasbora
Brevibora dorsiocellata
Balitoridae
Eyespotted Borneo sucker
Gastromyzon ocellatus
Cyprinidae
Eğirdir barb
Capoeta pestai
Callichthyidae
Fairy catfish
Corydoras atropersonatus
Cichlidae
Fairy cichlid
Aulonocara jacobfreibergi
Cichlidae
Fairy Cichlid
Biotoecus opercularis
Akysidae
Falcate chameleon catfish
Acrochordonichthys gyrinus
Cyprinidae
fallfish
Semotilus corporalis
Bagridae
False black lancer
Bagrichthys macropterus
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.