Balitoridae
Nan Hillstream Loach
Hemimyzon nanensis
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.
Nan Hillstream Loach
Cyprinidae
Nandi labeo
Labeo nandina
Gobiidae
Nantaiensis Goby
Rhinogobius nantaiensis
Cyprinidae
Narayan barb
Pethia narayani
Cyprinidae
Narrow striped rasbora
Rasbora microcephalus
Cyprinidae
Narrow-headed Altai osman
Oreoleuciscus angusticephalus
Cichlidae
Narrow-mouthed Natron tilapia
Oreochromis ndalalani
Plotosidae
narrowfront tandan
Neosilurus ater
Cyprinidae
nase
Chondrostoma nasus
Cyprinidae
Nase
Pseudochondrostoma willkommii
Cyprinidae
Nash's barb
Osteochilus nashii
Amphiliidae
Natal mountain catfish
Amphilius natalensis
Cichlidae
Nautla cichlid
Herichthys deppii
Cyprinidae
Nazas chub
Gila conspersa
Cyprinodontidae
Nazas Pupfish
Cyprinodon nazas
Catostomidae
Nazas sucker
Pantosteus nebuliferus
Cichlidae
Ncheni Haplo
Dimidiochromis dimidiatus
Adrianichthyidae
Nebulosus ricefish
Oryzias nebulosus
Poeciliidae
Needle toothcarp
Brachyrhaphis rhabdophora
Terapontidae
Neil's grunter
Scortum neili
Salmonidae
Neiva
Salvelinus neiva
Bagridae
Nekogigi
Coreobagrus ichikawai
Nemacheilidae
Nemacheilus insignis
Oxynoemacheilus insignis
Nemacheilidae
Nemacheilus leontinae
Oxynoemacheilus leontinae
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.