Darters are small freshwater fish of the perch family. Their name comes from their swimming behavior, moving from place to place on the bottom in sudden, quick spurts.

There are many species of darters, some very brightly colored. However, only one – the tessellated darter – is found in the tidal Hudson. It is a slender fish, sandy brown in color, with dark X- or W-shaped markings along its sides. Three to four inches is the maximum length of this darter.

The tessellated darter lays its eggs on the undersides of stones, shells, and other objects. The male then guards the nest until the eggs hatch.