Bryconidae
Mourning tetra
Brycon pesu
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.
Mourning tetra
Doradidae
Mouse Catfish
Tenellus leporhinus
Rhamphichthyidae
Mousetail knifefish
Gymnorhamphichthys rondoni
Auchenipteridae
Moustache catfish
Auchenipterus nuchalis
Apogonidae
Mouth almighty
Glossamia aprion
Catostomidae
Moxostoma hamiltoni
Thoburnia hamiltoni
Cyprinidae
Mrigal carp
Cirrhinus mrigala
Poeciliidae
Mt. Nimba lampeye
Rhexipanchax nimbaensis
Cyprinidae
mud carp
Cirrhinus molitorella
Percidae
Mud darter
Etheostoma asprigene
Rivulidae
Mud Rivulus
Atlantirivulus janeiroensis
Centrarchidae
mud sunfish
Acantharchus pomotis
Umbridae
mud-minnow
Umbra pygmaea
Clariidae
Mudfish
Clarias anguillaris
Distichodontidae
Multibar citharine
Nannocharax multifasciatus
Cichlidae
Multispot Peacock Cichlid
Aulonocara gertrudae
Ailiidae
Murius vacha
Eutropiichthys murius
Percichthyidae
Murray cod
Maccullochella peelii
Atherinidae
Murray hardyhead
Craterocephalus fluviatilis
Melanotaeniidae
Murray River rainbowfish
Melanotaenia fluviatilis
Cyprinidae
Mursa
Luciobarbus mursa
Gasterosteidae
Musashi-tomiyo
Pungitius nakamurai
Percidae
Muscadine Darter
Percina smithvanizi
Esocidae
muskellunge
Esox masquinongy
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.