Centrarchidae
Northern sunfish
Lepomis peltastes
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.
Northern sunfish
Cichlidae
Northern Tanganyika Clown
Eretmodus marksmithi
Eleotridae
Northern trout gudgeon
Mogurnda mogurnda
Cyprinidae
Northern whitefin gudgeon
Romanogobio belingi
Erythrinidae
Northern Wolffish
Hoplias microcephalus
Galaxiidae
Northland mudfish
Neochanna heleios
Cyprinidae
Notched mud carp
Henicorhynchus entmema
Catostomidae
Notchlip redhorse
Moxostoma collapsum
Cyprinidae
nothern squawfish
Ptychocheilus oregonensis
Acestrorhamphidae
Nova's Astyanax
Astyanax novae
Cichlidae
Nsess
Stomatepia mariae
Cyprinidae
Nueces roundnose minnow
Dionda serena
Cyprinidae
Nueces Roundnose Minnow
Dionda texensis
Cyprinidae
Nukta
Schismatorhynchos nukta
Cyprinidae
Numidian Barbel
Luciobarbus numidiensis
Alestidae
Nurse tetra
Brycinus nurse
Cyprinidae
Nyanza barb
Enteromius nyanzae
Cyprinidae
Nzoia barb
Enteromius yongei
Eleotridae
Oaxaca cave sleeper
Caecieleotris morrisi
Cichlidae
Oaxaca cichlid
Vieja zonata
Profundulidae
Oaxaca Killifish
Profundulus oaxacae
Cichlidae
Obama’s Teleogramma
Teleogramma obamaorum
Plotosidae
Obbes' catfish
Porochilus obbesi
Cichlidae
Obliquidens Hap
Haplochromis obliquidens
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.