Fundulus zebrinus Jordan & Gilbert, 1883

Species Identity

This species, Fundulus zebrinus (the plains killifish), generally grows to around 6.9 cm (2.7 inches) long, and reaches a maximum total length of 8–10 cm (3.1–3.9 inches).

Size & Lifespan

It can live up to 3 years, though most individuals do not live past 2 years of age.

Head Morphology

It has a flat head with a protruding jaw that lets it feed at the water surface.

Base Coloration

The species is variable in color, with individuals being brown, black, greenish, or straw-colored, and having a paler yellowish or silvery belly.

Striped Markings

It is marked with 12 to 28 dark vertical stripes, which give the species its scientific name meaning "like a zebra".

Sexual Color Dimorphism

Males have wider, darker bars than females. Breeding males develop bright orange color on most of their fins.

General Diet

The killifish feeds on chironomid larvae, copepods, nematodes, other small animals, and also consumes plant matter as a herbivore.

Substrate Feeding Behavior

It may feed by scooping up and swallowing mouthfuls of riverbed substrate to reach buried food items. It usually spits out most sand and undigestible material, but its digestive tract still typically contains some amount of sand.

Mosquito Control Potential

When available, it eats mosquito larvae, and research suggests it could be useful for mosquito abatement work.

Aquatic Habitat Range

It occupies a variety of shallow river and stream habitat types, and can live in lower, moderate, and swift, turbid water flows. It can also be found in lakes.

Water Chemistry Tolerance

It is more tolerant of brackish, alkaline, and salty water than most other co-occurring fish species.

Substrate Burying Behavior

It can bury itself in the stream substrate, leaving only its eyes and mouth exposed.

Burying Behavior Functions

This behavior is thought to be a possible stress response, and may also protect the fish from sunlight, heat, predators, or low water levels, or help it remove parasites.

Predator Impact

Populations of this killifish drop where the predator green sunfish (Lepomis cyanellus) is present.

Spawning Trigger

Spawning is triggered by water temperature, typically occurring when temperatures rise above 26 °C (79 °F).

Spawning Season

The spawning season runs from April through August.

Known Parasites

A number of parasites have been recorded infecting this species.

Gill Parasites

Gills are infested by the myxozoan Myxosoma funduli, the protozoan Trichodina species, the fluke Urocleidus fundulus, and the monogenean Gyrodactylus bulbacanthus.

Non-Gill Parasites

Gyrodactylus stableri infests the fins, while flukes of the genus Neascus infest the fish's eye and internal tissues.

New Parasite Description

The monogenean gill parasite Salsuginus thalkeni was first formally described from specimens collected from this killifish.

Historical Taxonomic Classification

For a long time, individuals of the closely related Fundulus kansae were classified as part of F. zebrinus, with the two names treated as synonyms; F. kansae was sometimes also considered a subspecies of F. zebrinus.

Taxonomic Separation Evidence

Molecular and genetic studies have since supported separating the two species.

Morphological Differences from F. kansae

F. zebrinus is slightly larger than F. kansae, and has larger scales and larger eyes.

Breeding Male Color Differences from F. kansae

Breeding male F. zebrinus develop more red fin coloration, while breeding male F. kansae have more yellow-orange fin coloration.

Native Range Center

This species has a wide distribution, mostly across the central United States, with its native range centered in the Great Plains.

Native Drainage Distribution

Its native distribution covers much of the Mississippi River drainage, portions of the Colorado and Brazos Rivers, and some areas in the Rio Grande region, particularly the Pecos River.

Historical Distribution Drivers

Pleistocene changes to local river system geography, such as glaciation, shaped its current distribution.

Introduced Populations

Many recorded populations are the result of introductions, including populations at Lake Powell in Arizona and Utah, Fort Peck Reservoir in Montana, and multiple Colorado River tributaries in Colorado, Utah, and Nevada.

Uncertain Native Status

Some existing populations have an unclear native status.

Introduction Timeline

Purposeful and accidental introductions became common starting in the 1930s.

Introduction Cause

Most introductions happened when this species was used as bait by anglers, and the fish escaped into the wild to establish new populations.