Dalmatian molly

Care at a glance

Overview

A dalmatian molly is a white fish with irregular black spots and blotches, and the amount of black runs from mostly white fish to mostly black ones. No two carry the same pattern, and shops ship from a batch rather than the fish pictured, so the black on the fish that arrives rarely matches the listing photo. The same spotting is sold on standard, lyretail and balloon bodies, and some shops sell the look as marbled or salt-and-pepper molly. Mollies with the black laid out in streaks rather than blotches usually go by harlequin instead.

In the wild

Wild mollies are sometimes caught with black blotches. Breeders working in the late 1920s and early 1930s, Bill Schomberg of Crescent Fish Farm in New Orleans among the first, bred the blackest fish together until they had a solid black molly. Bill Allen, writing in Tropical Fish Hobbyist, traces the marbled molly to the part-blotched fish thrown along the way and has seen the same fish sold as salt-and-pepper or dalmatian. Shop mollies are hybrids of the sailfin and short-finned species, so the label moves with the seller: most list the dalmatian as Poecilia latipinna, some as P. sphenops, and one shop files its standard fish under latipinna and its balloons under sphenops. No breeder, farm, country or date is on record for the dalmatian line itself.

Good to know

The black sits in macromelanophores, pigment cells about three times the size of the small ones that give a molly its normal gray, and where they overlap the spots merge into blotches. In a black-spotted wild sailfin pair from Key Largo, Florida, the spotting traced to a single gene with incomplete dominance and very uneven expression; no study has tested trade dalmatians for it. Wild spotted sailfins are born unspotted, reach the full pattern only after maturity and keep adding black with age, males more than females. Keepers see the same darkening in dalmatians, some almost fully black within six or seven months. Marbled mollies bred together throw fry from solid black to no black at all, so the pattern does not come true.

Common questions

Related species

• 

  Black molly

  Poecilia sphenops

  4.7 in (12 cm) · 24 gal (90 L)

  4.7 in (12 cm)24 gal (90 L)70–82°F (21–28°C)

• 

  Liberty molly

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  3.9 in (10 cm) · 24 gal (90 L)

  3.9 in (10 cm)24 gal (90 L)72–82°F (22–28°C)

• 

  Giant sailfin molly

  Poecilia velifera

  5.9 in (15 cm) · 30 gal (113 L)

  5.9 in (15 cm)30 gal (113 L)75–82°F (24–28°C)

• 

  Shortfin molly

  Poecilia mexicana

  4.3 in (11 cm) · 32 gal (120 L)

  4.3 in (11 cm)32 gal (120 L)72–82°F (22–28°C)

• 

  Gill's molly

  Poecilia gillii

  3.9 in (10 cm) · 26 gal (100 L)

  3.9 in (10 cm)26 gal (100 L)72–86°F (22–30°C)

• 

  Amazon molly

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  3.5 in (9 cm) · 20 gal (75 L)

  3.5 in (9 cm)20 gal (75 L)68–82°F (20–28°C)