Cichlidae
Blue Victoria mouthbrooder
Haplochromis nubilus
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.
Blue Victoria mouthbrooder
Cetopsidae
Blue Whale Catfish
Cetopsis coecutiens
Cichlidae
Blue-eye cichlid
Cryptoheros spilurus
Loricariidae
Blue-eye panaque
Panaque suttonorum
Loricariidae
Blue-eyed plec
Panaque cochliodon
Loricariidae
Blue-eyed Redfin Pleco
Hypostomus soniae
Cichlidae
Blue-eyed Tropheus
Tropheus brichardi
Cichlidae
Blue-point Flag Cichlid
Andinoacara coeruleopunctatus
Rivulidae
blue-striped rivulus
Laimosemion xiphidius
Elassomatidae
Bluebarred pygmy sunfish
Elassoma okatie
Acestrorhamphidae
Blueberry tetra
Hyphessobrycon wadai
Percidae
Bluebreast darter
Etheostoma camurum
Percidae
Blueface darter
Etheostoma cyanoprosopum
Fundulidae
bluefin killifish
Lucania goodei
Nothobranchiidae
Bluefin notho
Nothobranchius rachovii
Cyprinidae
Bluefin stoneroller
Campostoma pauciradii
Channidae
Bluefinned snakehead
Channa bleheri
Centrarchidae
Bluegill
Lepomis macrochirus
Percidae
Bluegrass darter
Etheostoma jimmycarter
Cichlidae
Bluegray mbuna
Pseudotropheus johannii
Poeciliidae
Bluegreen lampeye
Procatopus aberrans
Cyprinidae
bluehead chub
Nocomis leptocephalus
Cyprinidae
Bluehead shiner
Pteronotropis hubbsi
Catostomidae
Bluehead sucker
Pantosteus discobolus
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.