Poeciliidae

Chocolate Molly

Poecilia sphenops

A form of:Molly sphenops

Among the numerous selective breeding forms of mollies, the Chocolate Molly is frequently encountered, also known in the trade as Chocolate Molly. Its characteristic feature is the brownish coloration of its body and fins. This color can appear unevenly, sometimes resembling a fusion of chocolate speckles, or it can vary from light to dark shades, and at times include pigments of other tones, such as red.

Tank
from 150 L (40 gal)
Temperature
21 – 26 °C (70 – 79 °F)
Size in aquarium
8 – 12 cm (3.1 – 4.7 in)
Acidity
pH 7–8.5
Natural rangeRange on the map
  • Central America area
  • Colombia
  • Cook Islands
  • Curaçao
  • El Salvador
  • Honduras
  • Mexico
  • Nicaragua
  • Venezuela

Tank conditions

Plan the tank stocking
Temperature
21 – 26 °C (70 – 79 °F)
Water pH
Neutral (7) – Slightly alkaline (8.5)
Water dH
Hard (15) – Very hard (30)
Water salinity
low (3–5 g/L)
Size in aquarium
8 – 12 cm (3.1 – 4.7 in)
Lifespan
4 years
Temperament
Peaceful (regular)
Toward small fish
not a predator
Required aquarium volume
from 150 L (40 gal)
Lighting
any
Substrate
any (no restrictions)
Water flow
weak
Swimming level
near the surface
Feeding
Mixed diet meat + plant-based
Keeping
Mixed solitary / pair / group
Jumping
high a tight-fitting lid is essential
  • Lifespan. A lifespan to expect under good care, not a measured value: it depends heavily on tank volume, water quality and diet — and for selectively bred forms, on their origin as well.
  • Toward small fish. Based on the Predators category in the catalog or the temperament in the species parameters. “A risk to small fish” means the species is not a predator by habit, yet will swallow any fish that fits in its mouth.
  • Required aquarium volume. This is a husbandry recommendation, not a measured value: the volume depends on the keeping mode (mixed (solitary / pair / group)), footprint, decor and tank mates.

Care and keeping

Description

The Chocolate Molly is a selectively bred variation of the species Poecilia sphenops. The fish have an elongated body, moderately compressed laterally, and rounded fins. The coloration is characterized by rich chocolate or dark brown hues, sometimes with a velvety sheen. Sexual dimorphism is clearly expressed: males are slimmer and smaller than females, possessing a modified anal fin — the gonopodium, while females are larger, more massive, and have a rounded abdomen.

Habitat

The natural species Poecilia sphenops inhabits fresh and brackish waters of Central and South America, including territories from Mexico to Colombia and Venezuela. In nature, the fish are often found in coastal zones where fresh and marine waters mix. The chocolate form is a result of artificial selection and is not found in natural conditions.

Behavior and Compatibility

These are peaceful and active fish, suitable for a community tank with non-aggressive neighbors. Within the species, males may show increased attention to females, so it is recommended to keep them in groups with a predominance of females. The fish prefer to stay in the middle water layers and need an aquarium with sufficient free swimming space and plant thickets for shelter.

Care and Maintenance

In the wild, these fish prefer shallow waters abundant with dense aquatic vegetation. In a home aquarium, it is desirable to recreate a similar environment, arranging plant thickets in such a way that open areas remain for swimming. Females, juveniles, and fry can find shelter in these thickets. Large dominant males, striving for reproduction, may show excessive attention to females, so the presence of shelters for the latter becomes a necessity. In small tanks, for the same purpose, it is recommended to form a group based on the “harem” principle, where females predominate. Other aspects of aquarium design are left to the aquarist's discretion, based on their personal preferences and capabilities. The minimum permissible aquarium volume is determined by the specific species of molly. For example, for 3–4 Chocolate Mollienisia sphenops, 100 L will be sufficient, while Mollienisia velifera will require at least 150 L. As with most other aquarium inhabitants, successful keeping depends on several key factors: maintaining water purity with optimal pH and GH values, balanced nutrition, and the presence of peaceful tankmates. Dry foods (flakes, granules) with a high content of vegetable components can be used as the basis of the daily diet. A lack of plant food can lead to fish damaging delicate parts of aquatic plants. Coexistence with other livebearing species, such as Guppies, Platies, Swordtails, as well as with representatives of other groups of comparable size, is usually successful.

Diet

The species is omnivorous. The diet should include both animal and plant components. It is recommended to use high-quality dry foods with added spirulina or other vegetable ingredients, and also periodically offer blanched lettuce leaves, zucchini, or cucumbers. A lack of fiber can negatively affect the fish's digestion.

Breeding and Reproduction

Breeding is not difficult, as the species is livebearing. Fertilization occurs inside the female's body, after which she gives birth to fully formed fry. The incubation period lasts from 4 to 6 weeks. Since adults are prone to cannibalism, it is recommended to move the pregnant female to a separate breeding tank with dense vegetation, where the fry can find shelter.

Diseases

Fish are susceptible to typical livebearer diseases, including ichthyophthiriasis, fin rot, and fungal infections. The main cause of diseases is often non-compliance with water parameters or sharp temperature fluctuations. Prevention includes maintaining cleanliness, regular water changes, and observing quarantine when purchasing new specimens.

How to choose

When choosing, pay attention to the fish's activity, the cleanliness of their skin, and the absence of white film or damage to the fins. Healthy specimens should have a robust physique and show interest in food. Avoid purchasing fish with signs of emaciation, clamped fins, or unnatural behavior, such as prolonged hovering in one place or attempts to rub against the substrate.

Frequently asked questions

The essentials: size, tank volume, water parameters and care

How big does Chocolate Molly get?

An adult reaches 8–12 cm in length. Plan the tank around the maximum size: the fish quickly outgrows a cramped setup.

What size aquarium does Chocolate Molly need?

The recommended volume is 150 L. A smaller tank speeds up nitrate build-up and raises stress levels.

What water parameters does Chocolate Molly need?

Temperature 21–26 °C, pH 7–8.5, hardness 15–30 dGH. Stability matters more than exact values: sudden swings are harder on the fish than a small deviation from the ideal.

How long does Chocolate Molly live?

Around 4 years when kept properly. Lifespan depends directly on tank volume, water quality and a varied diet.

Is Chocolate Molly aggressive?

Temperament: peaceful (regular). Keep this in mind when choosing tank mates.

How many Chocolate Molly should be kept together?

Recommended setup: mixed (solitary / pair / group). Ignoring this is a common cause of stress and disease.

What does Chocolate Molly eat?

Diet type: mixed diet (meat + plant-based). Feed small portions that are finished within a couple of minutes — overfeeding does more harm than underfeeding.

What is the scientific name of Chocolate Molly?

The scientific name of the species is Poecilia sphenops, family Poeciliidae. It also appears in the literature as: Gambusia modesta, Gambusia plumbea, Lembesseia parvianalis.

Similar fishes

Matched by family, categories and overlapping keeping conditions

Balloon Molly

Balloon Molly

Poecilia sphenops

Poeciliidae

The Balloon Molly, also known as the Balloon Molly, is called the Balloon Molly in English-speaking trade. This common name is given to selective breeding forms obtained by breeding based on Poecilia sphenops, Poecilia…

Black and White Molly

Black and White Molly

Poecilia sphenops

Poeciliidae

The Black and White Molly is a collective name for several selectively bred forms distinguished by their characteristic body colouring dominated by black and white tones. Examples of these forms include the Dalmatian…

Black and Yellow Molly

Black and Yellow Molly

Poecilia sphenops

Poeciliidae

The Black and Yellow Molly, also known as Gold Dust Molly, takes its names from English trade names: Gold and Black Molly Fish and Gold dust molly. These names refer to a colour form of Poecilia sphenops distinguished…

Black Molly

Black Molly

Poecilia sphenops

Poeciliidae

The black molly, often simply called Black Molly, is apparently a selectively bred colour variant of the common molly, Poecilia sphenops. Some experienced breeders argue instead that it descends from Poecilia latipinna.…

Other scientific names and conservation status

Other scientific names
Gambusia modesta, Gambusia plumbea, Lembesseia parvianalis, Mollienesia altissima, Mollienesia macrura, Mollienesia pallida
Categories
Livebearers
Conservation status
Least concernLC