Freshwater

Alaska blackfish

Dallia pectoralis

The Alaska blackfish can be identified by its short, flattened snout, the posterior position of the …

Argentine pearlfish

Austrolebias bellottii

The Argentine pearlfish has a laterally compressed, fusiform (spindle-shaped) body with a rounded profile. Males are …

Black Molly

Poecilia sphenops

The Black Molly has an elongated body. Females tend to be more rounded in appearance. The …

Constancia’s seasonal killifish

Cynolebias constanciae

The body of Constancia's seasonal killifish (Cynolebias constanciae) is elongate and slightly laterally compressed.

Eastern mosquitofish

Gambusia holbrooki

The body of the Eastern mosquitofish is moderately elongated, not tall, and laterally compressed. It is …

Finescaled four-eyed fish

Anableps microlepis

Anableps: Greek, ana = up + Greek, blepo, blepsis, -eos = glance, sight.The elongated cylindrical body …

Grass pickerel, Redfin pickerel

Esox americanus vermiculatus, Esox americanus americanus

Thin and cylindrical, grass and redfin pickerel look very similar to chain pickerel, with the same …

Green swordtail

Xiphophorus hellerii

Green swordtails have elongated, narrow bodies that are flattened on the sides. They also have large …

Guppy

Poecilia reticulata

Guppies exhibit pronounced sexual dimorphism, with males and females differing in size, shape, and colouration. Males …

Least killifish

Heterandria formosa

Least killifish differ little in body shape from their closest relatives, the Poecilia. They have an …

Mosquitofish

Gambusia affinis affinis

The male anal fin is modified and is an intermittent organ for introducing sperm into the …

Muskellunge

Esox masquinongy

The muskellunge has an arrow-shaped body, long and smooth. The single dorsal fin with soft rays …

Muskellunge, Tiger

Esox masquinongy x Esox lucius

Tiger muskellunge was thought to be a separate species until scientists were able to cross northern …

Pickerel, Chain

Esox niger

With its long, slender body, chain pickerel resembles northern pike and muskellunge, especially when young. It …

Pike, Northern

Esox lucius

The northern pike has an elongated body and head. The snout is broad and flat, resembling …

Porous seasonal killifish

Cynolebias porosus

The Porous seasonal killifish has a fusiform (spindle-shaped) body that is laterally compressed. The snout is …