Freshwater

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 …

Herring

Clupea

Body compressed from the sides, with jagged edge of abdomen. Scales moderate or large, rarely small. …

Ide

Leuciscus idus

The body of the ide is thick. It is distinguished by the following features: a shortened …

Ladyfish

Elops saurus

The ladyfish has an elongated, slender, silvery body with a blue-green back and fine scales. It …

Lamprey: Sea Lamprey

Petromyzon marinus

Fish without jaws are fish-like vertebrates, eel-like in shape, with a cartilaginous or fibrous skeleton in …

Least cisco

Coregonus sardinella

The body of the Least Cisco is elongated, somewhat compressed at the sides, with the greatest …

Least killifish

Heterandria formosa

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

Mango tilapia

Sarotherodon galilaeus

The mouth is small, with the lower jaw length being less than 1/3 of the total …

Minnow, Fathead

Pimephales promelas

The fathead minnow has a puny, deep, compressed body with a short, flattened head. The snout …

Minnow: Golden Shiner

Notemigonus crysoleucas

Minnows are characterized by a single dorsal fin, pelvic fins, soft fin rays, cycloid scales, and …

Mosquitofish

Gambusia affinis affinis

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

Mullet

Mugil cephalus, Mugil curema

The striped mullet (Mugil cephalus) has a bluish-gray or green coloration along the back, turning to …

Muskellunge

Esox masquinongy

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

Ninespine Stickleback

Pungitius pungitius

The stickleback gets its name from the short and long spines on the first dorsal fin, …

One-lined pencilfish

Nannostomus unifasciatus

The name unifasciatus comes from the Latin words uni ("one") and fasciatus ("banded"), meaning "one-banded." The …

Paradise fish

Macropodus opercularis

This species exhibits sexual dimorphism. Males are larger than females and possess elongated filaments on their …

Perch, White

Morone americana

The white perch has a deep, thin body that rises steeply upward from each eye to …

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 …

Piraya

Pygocentrus piraya

The piraya has a laterally compressed, roughly circular profile typical of piranhas. A distinctive feature is …

Predatory carp

Chanodichthys erythropterus

The predatory carp has a body structure typical of an active pelagic predator — streamlined, elongated, …

Pyrrhulina filamentosa

Pyrrhulina filamentosa

Pyrrhulina filamentosa has an elongated body with a large caudal fin, the upper lobe of which …

Red-bellied piranha

Pygocentrus nattereri

The red-bellied piranha has a short, deep body shape. Its cross-section is compressed.All piranhas have large …