Overview
The Molly (Poecilia sphenops) is a freshwater fish belonging to the family Poeciliidae. It thrives at temperatures of 24–28 °C with a pH of 7.0–8.5, and requires a minimum tank volume of 75 litres. Known for its peaceful community fish; benefits from hard alkaline water, it is considered a beginner-level species. Adding 1–2 tablespoons of aquarium salt per 10 litres improves health and disease resistance. Water changes of 25–30 % weekly, stable parameters, and appropriate tank mates are key to long-term success with this species.
Scientific Classification
| Rank | Classification |
|---|---|
| Family | Poeciliidae |
| Genus | Poecilia |
| Species | Poecilia sphenops |
| Water type | freshwater |
| Native range | Caribbean|Oceania|Neotropical|Oriental (Indomalaya)|Palaearctic|Pacific (Oceania)|Gulf of Mexico|Macrocuenca Magdalena-Cauca ||Girón |
Natural Habitat
Poecilia sphenops originates from Caribbean|Oceania|Neotropical|Oriental (Indomalaya)|Palaearctic|Pacific (Oceania)|Gulf of Mexico|Macrocuenca Magdalena-C. It inhabits freshwater environments and is adapted to the water conditions found in its native range.
Appearance
Adults reach Males 6–8 cm; females 8–12 cm in length. The body is freshwater and the species displays characteristic coloration suited to its environment.
Behavior
This species is described as a peaceful community fish; benefits from hard alkaline water. It does not school and can be kept individually or in small numbers. Activity level is moderate. Adding 1–2 tablespoons of aquarium salt per 10 litres improves health and disease resistance.
| Trait | Value |
|---|---|
| Temperament | peaceful community fish; benefits from hard alkaline water |
| Schooling | No |
| Activity level | moderate |
Water Requirements
| Parameter | Ideal Range | Notes |
|---|---|---|
| Temperature | 24–28°C (75–82°F) | Use a reliable adjustable heater |
| pH | 7–8.5 | Avoid sudden swings |
| Hardness (GH) | 15–30 dGH dGH | Soft to moderately hard |
| Ammonia | 0 ppm | Any detectable ammonia signals a problem |
| Nitrite | 0 ppm | Toxic even at low levels |
| Nitrate | <25 ppm | Manage through regular partial water changes |
| Min. tank | 75L (20 gal) | Larger tanks are easier to keep stable |
Interesting Facts
- Mollies are one of the few freshwater fish that readily adapt to full marine saltwater.
- The Sailfin Molly (Poecilia latipinna) is a closely related species often sold interchangeably.
- Black Mollies are entirely melanistic colour forms developed through selective breeding.
📋 Full Care Guide
Ready to set up a tank for your Molly? The complete care guide covers tank setup, feeding schedule, common diseases, tank mates, and breeding.
Read Molly Care Guide →Related Species
Related Species & Guides
This species profile was reviewed for biological accuracy and practical aquarium care guidance. For suspected illness or disease, test your water parameters first and consult an aquatic veterinarian if symptoms persist.