Its scientific name derives from the Latin word "fundus," which literally means "bottom," and many view this as ironic since the fish is a type of topminnow.

Living mostly in shallow waters, the male bayou killifish displays bright striped patterns of silver and olive-green, while the females are uniquely spotted.

Unlike many other minnows, the bayou killifish usually grows to a maximum length of 5–7 centimetres (2.0–2.8 in), enabling it to have the size it needs to defend itself, as well as the maneuverability of a much smaller fish.

Males display an olive-green coloration on the top half of the body near the dorsal fin, with gold sides and a silvery bottom.

All seven species belonging to Fundulus, including the bayou killifish, are native to the Gulf coast and Atlantic waters of North America.

What makes them different from other killifish genera is the formation of the maxilla, a bone that helps form the upper jaw of the fish.

In F. pulvereus and other species belonging to the subgenera "Fundulus", the maxilla has a distinctly concave edge near the back of the bone, toward the brain.

[7] Just as the name implies, the bayou killifish predominates many freshwater and brackish environments such as bays, marshes, swamps, and bayous along the Atlantic coast.

[6] However, due to a remarkable adaptation of the killifish's lungs, the species is also capable of inhabiting marine environments such as saltwater marshes and oceans.

[5] Most populations of bayou killifish can be found in the temperate coastal waters of the Atlantic coast of North America, as well as the Gulf of Mexico.

Isopods, small crustaceans that usually live on the bottom of freshwater and marine environments, serve as the primary food source for the bayou killifish for several reasons.

Dating back to Carboniferous period 300 million years ago, many aquatic isopods have evolved to live in unstable environments.

Possibly a future threat for the Bayou Killifish C. fuduli shows no recent negative impact on F. pulvereus other than taking up significant space in the digestive tract.

[5] Due to their size and maneuverability, Bayou Killifish are able to avoid the few predators that they do have, a defense mechanism crucial to the survival of the species.