Sternopygidae
Glass knifefish
Eigenmannia virescens
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.
Glass knifefish
Acestrorhamphidae
Glass Phantom Tetra
Moenkhausia hemigrammoides
Characidae
Glass Piquira
Spintherobolus ankoseion
Characidae
Glass sardine
Roeboides dayi
Schilbeidae
Glass schilbid
Parailia pellucida
Acestrorhamphidae
Glass tetra
Moenkhausia oligolepis
Characidae
Glass tetra
Phenacogaster wayana
Cyprinidae
Glass-barb
Pethia guganio
Percidae
Glassy darter
Etheostoma vitreum
Plotosidae
Glencoe tandan
Neosilurus hyrtlii
Cyprinidae
glowlight danio
Danio choprae
Cyprinidae
Glowlight rasbora
Trigonostigma hengeli
Acestrorhamphidae
Glowlight Tetra
Hemigrammus erythrozonus
Alestidae
Glutton Robber
Petersius conserialis
Aspredinidae
Gnarled catfish
Bunocephalus verrucosus
Cyprinidae
Gnathopogon notacanthus
Paraleucogobio notacanthus
Siluridae
Goan catfish
Ompok malabaricus
Loricariidae
Goatee Whiptail Catfish
Loricaria cataphracta
Apteronotidae
Goeldi’s tube-snouted ghost knifefish
Sternarchorhynchus goeldii
Ritidae
Gogra rita
Rita gogra
Cyprinidae
Gokcha barbel
Barbus cyri
Potamotrygonidae
Gold Dust Stingray
Potamotrygon marinae
Acestrorhamphidae
Gold Line Scissor Tail
Moenkhausia intermedia
Cichlidae
Gold Nasuta
Ophthalmotilapia nasuta
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.