Topsmelt Silverside

Atherinops affinis

The topsmelt silverside is a slim, surface-loving fish that grows to about 37 cm. Its back is a striking bright green, setting off silvery flanks and a pale belly, and it carries two separate dorsal fins, golden-yellow gills, and a blunt, rounded snout with small extendible jaws. There is no lateral line - instead a row of 63 to 65 scales marks where one would sit. Juveniles are nearly transparent with three rows of pigmented scales along the back. It ranges along the eastern Pacific from Vancouver Island south to Baja California and into the Gulf of California, and it is one of the most adaptable fish on that coast: common in estuaries, kelp forests, along sandy beaches and around pier pilings, and tolerant of water saltier than the sea, having been recorded living in evaporation ponds at 80 parts per thousand. Divers almost always find it in the upper 9 m, often in loose silver schools just under the surface. It moves into estuaries through spring and summer and back out to open coastline and kelp beds in autumn and winter. Spawning runs from March to October, at night over submerged vegetation. Young fish take zooplankton; adults forage closer to the bottom on algae, amphipods and midge larvae. Watch for them skipping clear of the water when mackerel or jacks push through.