Dalmatian molly

Care at a glance

Overview

The Dalmatian molly is a white fish with irregular black spots and blotches, from mostly white fish to mostly black ones. No two carry the same pattern, and shops ship from a batch, so the fish that arrives rarely matches the listing photo. It is easy to keep in a community tank.

Caring for the Dalmatian molly

Keep Dalmatian mollies in a group with more females than males, in a tank of at least 24 gal (90 L). They are social fish that cruise the middle and upper water, so leave open swimming room. They are mostly peaceful and safe in a community tank, though males can get pushy with each other.

Give them warm, hard, alkaline water at 70 to 79°F (21 to 26°C) and a pH of 7.0 to 8.0. They tolerate anything from fresh to brackish water. Some keepers add a little marine salt, though fish kept in fresh water do not strictly need it.

Dalmatian mollies graze a lot, so their diet should include algae and vegetable matter. Round it out with flake and the odd live or frozen treat.

They bear live young rather than laying eggs, and breeding them is easy. A female can produce a brood every few weeks.

Good to know

The Dalmatian molly's spotting is sold on standard, lyretail and balloon bodies. Mollies with the black laid out in streaks rather than blotches usually go by harlequin instead. The black sits in macromelanophores, pigment cells about three times the size of the small ones that give a molly its normal gray. 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 Dalmatian mollies 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 Dalmatian mollies, 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.

In the wild

The Dalmatian molly line has no breeder, farm, country or date on record. Wild mollies are sometimes caught with black blotches. Breeders in the late 1920s and early 1930s bred the blackest fish together until they had a solid black molly. Bill Schomberg of Crescent Fish Farm in New Orleans was among the first. Bill Allen, writing in Tropical Fish Hobbyist, traces the marbled molly to the part-blotched fish thrown along the way. He 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 and some as P. sphenops. One shop files its standard fish under latipinna and its balloons under sphenops.

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

  Poecilia salvatoris

  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

  Poecilia formosa

  3.5 in (9 cm) · 20 gal (75 L)

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