Rivulidae
Atlantic Coastal Rivulus
Atlantirivulus santensis
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.
Atlantic Coastal Rivulus
Salmonidae
Atlantic salmon
Salmo salar
Salmonidae
Atlas Trout
Salmo pellegrini
Nemacheilidae
Atrak crested loach
Paracobitis atrakensis
Cyprinidae
Attentive carplet
Amblypharyngodon melettinus
Percichthyidae
Aucha perch
Coreoperca kawamebari
Cichlidae
Aurora Cichlid
Maylandia aurora
Osteoglossidae
Australian pearl arowana
Scleropages jardinii
Percidae
Autumn Darter
Etheostoma autumnale
Gobionidae
Auvergne gudgeon
Gobio alverniae
Cichlidae
Avocado Cichlid
Amatitlania siquia
Botiidae
Ayumodoki
Parabotia curtus
Acestrorhamphidae
Azevedo's Jupiaba
Jupiaba apenima
Cyprinidae
Aztec chub
Aztecula sallaei
Cichlidae
Aztec cichlid
Herichthys molango
Acestrorhamphidae
Bacalar Tetra
Astyanax bacalarensis
Percidae
Backwater darter
Etheostoma zonifer
Badidae
Badis
Badis badis
Gobiidae
Baer pugolovka
Benthophilus baeri
Cyprinidae
bafa
Tropidophoxinellus spartiaticus
Ictaluridae
Bagre del panuco
Ictalurus australis
Bagridae
Bagrid Catfish
Chrysichthys maurus
Bagridae
Bagrid catfish
Chrysichthys nyongensis
Nemacheilidae
Bahaii Loach
Turcinoemacheilus bahaii
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.