How to Identify Molly

To identify Molly (Poecilia latipinna o Poecilia sphenops), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Wild P. latipinna are typically silvery-gray to olive-green with rows of dark spots on the flanks and fins. Wild P. sphenops are generally dull gray to olive. Cultivated varieties exhibit an immense range of colors including black, white, orange, yellow, marbled, and various metallic hues. 'Molly Dorato' likely refers to a golden or yellow variety.

Scale type

cycloid

Mouth position

superior

Distinctive features

Livebearer (gives birth to live young), Sexual dimorphism: Males are smaller, more slender, and possess a modified anal fin called a gonopodium for reproduction. Females are larger and rounder., P. latipinna males have a significantly enlarged, sail-like dorsal fin., P. sphenops has a shorter, more rounded dorsal fin.

Dorsal fin

P. latipinna: Large, sail-like, with 13-14 rays. P. sphenops: Shorter, rounded, with 8-10 rays. Cultivated forms can have varying dorsal fin sizes.

Tail fin

Rounded to lyre-shaped in some cultivated varieties. Wild forms typically have a rounded caudal fin.

Pectoral fin

Small, fan-shaped, located just behind the operculum.

Distinctive fins

Anal fin of males is modified into a gonopodium for internal fertilization.

Identification Tips

1. 1

   Dorsal Fin Size

   The most reliable way to distinguish wild P. latipinna from P. sphenops is the dorsal fin. P. latipinna (Sailfin Molly) has a very tall, sail-like dorsal fin with 13-14 rays, especially prominent in males. P. sphenops (Shortfin Molly) has a much shorter, rounded dorsal fin with 8-10 rays.

2. 2

   Body Shape and Size

   P. latipinna can grow larger, up to 15 cm (6 inches) for males, while P. sphenops typically reaches 6-10 cm (2.5-4 inches). Females are generally larger and more robust than males in both species.

3. 3

   Coloration (Wild vs. Cultivated)

   Wild mollies are usually drab, silvery-gray to olive. If you encounter a brightly colored or unusually shaped molly, it is almost certainly a cultivated variety or hybrid.

4. 4

   Gonopodium

   Males of both species possess a distinct, rod-like gonopodium (modified anal fin) used for reproduction, which is absent in females.

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