New York Natural Heritage Program
Atlantic Silverside
Menidia menidia (Linnaeus, 1766)
Ray-finned Fishes

Identifying Characteristics [-]
The Atlantic silverside is a small fish, approximately 3 to 6 inches (8 to 15 cm) in length. The upper sides are translucent green-yellow, gradually turning iridescent white on the sides to pale white on the underside. A metallic-silver stripe, bordered by a thin, dark line, runs along the length of the fish. The lateral line is composed of tubes passing through the lateral line scales. The posterior end of the dorsal fin is in front of the posterior end of the anal fin and the tail is forked. The eggs are small, ranging from 0.04 to 0.06 inches (0.9 to 1.5 mm) in diameter and are transparent yellow-green in color with tiny filaments. These filaments help the eggs adhere to aquatic vegetation located along shorelines and to each other (Fay et al. 1983, Smith 1985).

Characters Most Useful for Identification [-]
The tubular lateral line composition, higher lateral scale count, and the end of the dorsal fin being in front of the end of the anal fin are the most useful characteristics in distinguishing the Atlantic from the inland silverside (Smith 1985).

Best Life Stage for Proper Identification [-]
The adult is the best life stage for determining the differences between Atlantic and inland silversides.

Behavior [-]
Atlantic silversides are short-lived, generally dying in the winter after they spawn, although several two-year-old fish have been caught. Year zero fish migrate from the shallows of the estuaries to deeper offshore waters by winter. They come back to the shallows of tidal marshes the following spring and spawn in schools. Spawning generally occurs during the day at high tide and is centered around the lunar cycle, roughly starting during the first new or full moon phase of the spring. Between five and 20 spawning events can occur throughout the season, every 15 days or so, with individual females releasing up to 5,000 eggs total. Incubation time depends on water temperature, with eggs laid in higher temperatures hatching earlier than those laid in cooler temperatures. Growth rates vary with latitude and fish in the northern range grow faster than those in the southern part of the range, although they reach about the same maximum size throughout their range. To avoid predators, they form large schools and flee when approached (Conover et al. 2005, Fay et al 1983).

Diet [-]
Atlantic silversides feed in schools during the ebb tide on plankton composed of various amphipods, copepods, isopods, and insects (Carpenter 2002, Gilmurray and Daborn 1981).
Atlantic Silverside Images
click to enlarge
The Best Time to See
Atlantic silversides can be found in the shallows of the Hudson River estuary and other tidal rivers and creeks in southeastern New York and Long Island from the spring to the fall. They move out away from the shorelines and enter deeper water during the winter (Fay et al. 1983).
Active Reproducing
The time of year you would expect to find Atlantic Silverside active (blue shading) and reproducing (orange shading) in New York.
Similar Species
  • Inland Silverside (Menidia beryllina)
    The composition of the lateral line in the inland silverside is pit-like and there are fewer lateral scales. The end of the dorsal fin lines up with the end of the anal fin (Smith 1985).