Poeciliidae

Lyretail Molly

Poecilia sphenops

A form of:Molly sphenops

The Lyretail Molly, known in the English-speaking trade as LyreTail Molly, is a breed created artificially and has no natural counterparts. The subject of selection, presumably leading to its appearance, was the Sailfin Molly (Poecilia latipinna).

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 Lyretail Molly is a selective breeding form derived from the species Poecilia sphenops. Its characteristic feature is the lyre-shaped caudal fin, with elongated outer rays. The fish's body is robust, elongated, and laterally compressed. Coloration varies from velvety black to spotted or golden. Sexual dimorphism is distinctly expressed: males are smaller than females, have a pointed anal fin transformed into a gonopodium, and reach about 8-10 cm in length, while females can grow up to 12 cm or more.

Habitat

The wild species Poecilia sphenops inhabits fresh and brackish waters of Central and South America, from Texas to Colombia and Venezuela. In nature, these fish prefer coastal areas of rivers, estuaries, and lagoons with dense vegetation. Water parameters in their habitats are characterized by alkaline reaction and significant hardness. The species has high adaptability to water salinity, allowing it to survive in various biotopes.

Behavior and Compatibility

These are active, peaceful schooling fish that prefer to stay in the middle and upper water layers. For comfortable existence, it is recommended to keep them in a group with a predominance of females to reduce intraspecific aggression among males. They are compatible with most peaceful fish of similar size but may show territoriality or nip the long fins of slow-moving tank mates. The aquarium should have both open swimming areas and dense plant thickets for hiding.

Care and Maintenance

Females grow to about 10–12 cm and males to about 6–8 cm; the elongated rays of the caudal fin add to this length. From this, it follows that a group of 3–4 Lyretail Mollies will require an aquarium with a capacity of at least 100–150 liters. In this case, the rule applies: the larger the volume, the better. When decorating the tank, numerous shelters created by dense plant thickets and natural snags are preferred. The latter often become a place for algae to grow, which serves as an additional element in the fish's diet. Key keeping parameters: Aquarium volume: from 100–150 liters. Water temperature: 21–26°C. pH level: 7.0–8.5. Water hardness: medium to high (15–35 dGH). Substrate type: any. Lighting: any. Brackish water: adding salt is permissible, roughly 3–5 g per litre. Water movement: weak. Fish size: 8–12 cm. Diet: any food with essential plant components. Temperament: peaceful. Keeping: possible individually, in pairs, or in groups. Feeding. Fish require food rich in plant fibers. Sometimes they may damage delicate parts of aquarium plants in an attempt to satisfy this need. Specialized molly foods from reputable manufacturers will be an optimal choice. These products come in various forms, among which flakes and granules remain the most common and convenient. Warm, slightly alkaline water with a high level of general hardness is considered ideal. However, thanks to decades of selective breeding and adaptation to artificial conditions, Lyretail Mollies have successfully adapted to a wider range of parameters, including lower pH and dGH values. It is extremely important to prevent the accumulation of organic waste, as this can lead to a dangerous increase in nitrate levels. Regular aquarium maintenance is key to the health of its inhabitants. This includes weekly partial water changes, removal of food remnants and excrement. The continuous operation of the filtration system plays a crucial, and sometimes defining, role. Behavior and Compatibility. Males often exhibit competitive behavior for the attention of females. In small aquariums with few hiding places, it is recommended to keep a group consisting of one male and several females. These fish get along well with most peaceful species of comparable size. Avoid keeping them with fish known for their tendency to nip the long fins of other inhabitants, such as some species of barbs.

Diet

Mollies are omnivorous fish with a pronounced need for plant-based food. Their diet should include high-quality dry foods with a high content of spirulina or other plant components, as well as blanched vegetables (zucchini, spinach). Periodically, it is recommended to offer live or frozen foods, such as Artemia or bloodworms. Feeding frequency should be 2-3 times a day in small portions, as the fish are prone to overeating.

Breeding and Reproduction

Breeding is relatively simple, as the species is livebearing. Fertilization occurs inside the female's body with the help of the male's gonopodium. Pregnancy lasts 4-6 weeks, after which the female gives birth to fully formed fry. To preserve the offspring, it is recommended to use dense plant thickets or a breeding trap, as adult fish are prone to cannibalism. From the first days, fry are capable of feeding on Artemia nauplii, infusoria, or specialized finely crushed foods.

Diseases

Fish are sensitive to water quality and sudden temperature changes. They are often susceptible to ichthyophthiriosis (white spot disease) when stressed or chilled. Digestive problems can also arise from a lack of plant fiber in their diet. Prevention includes maintaining stable hardness and pH parameters, regular water changes, and adding aquarium salt (1-3 g per liter), which positively affects immunity and prevents fungal infections.

How to choose

When purchasing, choose active fish with clean fins, free of white spots, film, or ulcers on the body. It is important to pay attention to the condition of the abdomen — it should not be excessively sunken. The behavior of a healthy individual is characterized by curiosity and constant foraging. It is recommended to avoid fish that stay at the bottom, clamp their fins, or appear sluggish, as this may indicate health problems or recent transport stress.

Frequently asked questions

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

How big does Lyretail 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 Lyretail Molly need?

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

What water parameters does Lyretail 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 Lyretail Molly live?

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

Is Lyretail Molly aggressive?

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

How many Lyretail Molly should be kept together?

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

What does Lyretail 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 Lyretail 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.

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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