Apogonidae
Flathead cardinalfish
Apogon rubrifuscus
FISH SPECIES
Saltwater fish, also called marine fish, live in seas and oceans. They range from small reef residents to fast open-ocean swimmers and species that stay close to the seabed.
01 / NATURAL HISTORY
Marine fish regulate water and salts in a very different environment from freshwater fish. Body form often reflects where they live: streamlined swimmers cross open water, while compressed or camouflaged species maneuver around complex habitats.
02 / LIFESTYLE
Marine fish occupy a vast, three-dimensional environment with shifting currents, light gradients and depths. Open-water pelagic species often school to travel efficiently and confuse predators, while reef residents navigate complex crevices between foraging patches. Along the coast and continental shelves, tidal cycles and changing sunlight dictate daily peaks of activity and shelter seeking.
OBSERVATION INDEX
03 / SPECIES
Discover representative species illustrating the ecological diversity, morphologies and adaptations of this group.
Apogonidae
Apogon rubrifuscus
Pentanchidae
Apristurus macrorhynchus
Bovichtidae
Halaphritis platycephala
Pleuronectidae
Hippoglossoides dubius
Leptoscopidae
Lesueurina platycephala
Psychrolutidae
Ebinania australiae
Ariidae
Notarius insculptus
Peristediidae
Peristedion brevirostre
Eleotridae
Erotelis armiger
Pleuronectidae
Hippoglossoides elassodon
Ogcocephalidae
Malthopsis bulla
Tetraodontidae
Torquigener flavimaculosus
Pseudochromidae
Pseudoplesiops wassi
Dinematichthyidae
Dermatopsis macrodon
Dinematichthyidae
Dipulus norfolkanus
Triacanthodidae
Tydemania navigatoris
Pleuronectidae
Glyptocephalus cynoglossus
Orectolobidae
Orectolobus floridus
Blenniidae
Petroscirtes mitratus
Tetraodontidae
Torquigener florealis
Labridae
Cheilinus chlorourus
Muraenidae
Gymnothorax davidsmithi
Serranidae
Hypoplectrus floridae
Triakidae
Mustelus norrisi
04 / FIELD NOTES
Yes. Because surrounding seawater is saltier than their internal fluids, marine bony fish constantly lose water by osmosis, requiring them to drink seawater continuously and pump excess salts out via gill cells.
No. Coral reefs represent only a fraction of marine environments; the vast majority of marine species inhabit open pelagic waters, continental shelves, or the deep ocean floor.
Yes. Euryhaline and migratory species like salmon, bull sharks and European eels actively adjust their osmotic regulation between fresh and marine waters.