Menidia is a genus of silverside fish (Atherinopsidae) found all around the shores of the Gulf of Maine from Nova Scotia to Cape Cod.
The Menidia is six times as long as it is tall. Its body is covered with large, silver scales. Its fins are translucent bottle green, and the upper parts of the sides are speckled with dark brown. A silver band outlined by a narrow black streak runs alone each side of the Menidia. Its belly is smooth, rounded, and white. Its first dorsal fin, located halfway between the snout and the base of the caudal fin, is smaller than the second.
Menidia are often confused with young smelt. The two can be distinguished because the Menidia lacks the adipose fin of the smelt. Also, the Menidia has two dorsal fins – one spiny and one soft – while the smelt only has one soft dorsal fin.
Adult Menidia are an average of 4 to 4.5 in long, though they can grow to 5.5 in.
Menidia congregate in schools and travel along sandy or gravelly shores and in brackish water. They also swim in sedge grass at high tide, but they rarely venture out to sea. During the summer, Menidia ordinarily do not descend deeper than 6 ft. In winter, they have been reported to venture as far as 30 to 72 ft for warmth, but this is not typical behavior.
Menidia are omnivorous. They feed chiefly on copepods, mysids, shrimps, decapods, amphipods, Cladocera, fish eggs (including their own), young squid, annelid worms, insects that fall into water, algae and diatoms mixed with mud and sand, and molluscan larvae.
Natural predators of the Menidia are every predaceous fish that comes inshore – chiefly the striped bass and bluefish.
Menidia span in May, June, and Early July on the southern New England Coast. To reproduce, they gather in schools and deposit their eggs on the sandy sea floor, often among sedge grass at high tide or above the low-water mark.