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Sailfin molly (Poecilia latipinna)

The sailfin molly is an introduced ornamental fish recorded in Australia, where it has been collected at at least three locations. Its broad environmental tolerances and potential for adverse effects on native fish make it relevant to Australian land managers.

Key facts

Type: Pest animal, fish.

Native to: Atlantic and Gulf Coast drainages from North Carolina to the Yucatán Peninsula, Mexico..

Established in: QLD, WA.

Other names: Brazillebiste, topote velo negro, bubuntis, tabai.

Identification

  • It has an oblong body, a dorsally flattened head and a small upturned mouth.
  • Mature males may have a greatly enlarged dorsal fin, although not all males develop one.
  • Wild fish are generally light grey or olive, sometimes with rows of brown spots along the sides and spots on the dorsal and caudal fins.
  • Spots may merge or sit close together, giving the sides a striped appearance.
  • Males grow to about 100 mm and females to about 120 mm, although wild fish are typically smaller.
  • Look-alike: Other mollies, including Poecilia mexicana, P. petenensis and P. velifera, can look similar; P. velifera males also have a sailfin but grow larger.
  • Look-alike: Small fish may superficially resemble other introduced livebearers, including Gambusia and Xiphophorus species.

Where it lives

In Australia, it has been collected at sites including Majors Creek, about 50 km south-east of Townsville, and elsewhere can inhabit creeks, drains, ponds, lakes, marshes, swamps and brackish estuaries, often in shallow water near floating vegetation or other cover.

Why it matters

  • The species has been identified as having potential for adverse effects on some native fish in Australia.
  • The datasheet describes competition for food and other possible changes to aquatic biodiversity and food webs as concerns associated with introduced populations.
  • Outside Australia, reported concerns include competition with native milkfish in the Philippines and contribution to the decline of desert pupfish in California.

How it spreads

  • Release of unwanted ornamental fish is considered a likely explanation for non-native populations in Australia and some US states.
  • The species is popular in the Australian aquarium trade, and natural dispersal or human-assisted movement may spread established populations.
  • Flooding may assist natural dispersal; accidental escape from outdoor aquaculture ponds during drainage or floods is also described as a possible pathway.

Control methods

  • The datasheet does not describe a field eradication method or chemical control for established populations.
  • For aquaculture facilities, proposed safeguards include routing effluent through an underground or above-ground dry well.
  • It also proposes installing a sand-and-gravel filter that allows water through but not fish, and diking outdoor ponds on floodable land.
  • Promoting environmental awareness among people involved with ornamental fish farms is another proposed prevention measure.

Site hygiene and welfare

  • Keep live fish out of water discharges by routing effluent through a dry well or a sand-and-gravel filter that passes water but not fish.
  • Use methods set out in the national model codes of practice and standard operating procedures for the species.
  • Coordinate control with neighbours and the local government biosecurity plan, as isolated effort is quickly undone by reinvasion.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: General biosecurity duty. Not prohibited matter in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Not a declared pest. Not a declared pest or prohibited matter in Tasmania. Importing animals is still controlled by Biosecurity Tasmania.
  • Northern Territory: Not a declared pest. Not on an NT declared or prohibited list. Check with the NT Government before keeping, moving or releasing it.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources