Cichlidae
Flag cichlid
Mesonauta festivus
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.
Flag cichlid
Cichlidae
Flag Cichlid
Mesonauta insignis
Acestrorhamphidae
Flag tetra
Hyphessobrycon heterorhabdus
Prochilodontidae
Flag-Tailed Prochilodus
Semaprochilodus varii
Cyprinidae
Flagfin shiner
Pteronotropis signipinnis
Callichthyidae
Flagtail catfish
Dianema urostriatum
Acestrorhamphidae
Flagtail Tetra
Moenkhausia bonita
Cyprinidae
Flame chub
Hemitremia flammea
Poeciliidae
Flame Gambusia
Gambusia pyrros
Rivulidae
Flame rivulus
Cynodonichthys uroflammeus
Characidae
Flame tail tetra
Aphyocharax erythrurus
Alestidae
Flametail Featherfin Tetra
Bryconaethiops macrops
Catostomidae
Flannelmouth Sucker
Catostomus latipinnis
Cyprinidae
Flat Bitterling
Acheilognathus rhombeus
Ictaluridae
Flat bullhead
Ameiurus platycephalus
Loricariidae
Flat-head
Dekeyseria scaphirhyncha
Nemacheilidae
flat-headed loach
Oreonectes platycephalus
Crenuchidae
Flatfin Darter
Characidium alipioi
Ictaluridae
flathead catfish
Pylodictis olivaris
Cyprinidae
flathead chub
Platygobio gracilis
Galaxiidae
flathead galaxias
Galaxias depressiceps
Galaxiidae
Flathead galaxias
Galaxias rostratus
Salmonidae
Flathead trout
Salmo platycephalus
Claroteidae
Flatnose catfish
Notoglanidium macrostoma
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.