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Montana Field Guide

Montana Field Guides

Shortfin Molly - Poecilia mexicana

Non-native Species

Global Rank: G5
State Rank: SNA

Agency Status

External Links

General Description
This tropical aquarium fish is an illegally released pet fish. The native range is southeastern United States, Mexico, and Central America.

Diagnostic Characteristics
Specimens from Montana waters have been nearly all black or heavily blotched with black on body and fins. Some have orange on tail fin.

Observations in Montana Natural Heritage Program Database
Number of Observations: 6

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Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Can exist in Montana only in warm springs of ponds and streams resulting from these.

Food Habits
Diet varied. Feeds on both plant and animal matter. Vascular plants and mosquito larvae are important items in the diet.

Reproductive Characteristics
Reaches Sexual maturity at 1.5 - 2 in. in length. Under suitable conditions may produce several broods a year. Fertilization internal; young born alive.

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Citation for data on this website:
Shortfin Molly — Poecilia mexicana.  Montana Field Guide.  .  Retrieved on , from