Fundulus majalis

The striped killifish (Fundulus majalis), also called the striped mummichog, is a North American species of fundulid killifish. It lives in salt and brackish waters in shallow coastal regions from New Hampshire to Florida, and in the northern Gulf of Mexico.

It exhibits sexual dimorphism, with the males having vertical black stripes and the mature females having horizontal black stripes along the sides of their silver-colored bodies. Juvenile females have vertical stripes, however, and one or two vertical stripes remain at the end of the tail even on adult females. Striped killifish typically reach lengths of up to 6 in (15 cm), occasionally 7 in (18 cm).