Got a photo? Identify fish instantly with the Fishby app.
Open the appDescription
Poeciliopsis gracilis, commonly known as the Porthole Livebearer, is a small, slender freshwater fish belonging to the family Poeciliidae. It is characterized by its somewhat translucent body and a series of dark spots or 'portholes' along its flanks. This species is known for its viviparous reproduction, a common trait among livebearers, where females give birth to live, free-swimming young.
Physical Characteristics
- Body shape
- elongated
- Coloration
- The body is typically translucent to yellowish-brown, often with a silvery sheen. A distinctive feature is a series of 6-10 dark, often somewhat rectangular or oval, spots (the 'portholes') along the lateral line. Fins are generally clear or slightly yellowish. Males may exhibit more intense coloration during breeding.
- Scale type
- cycloid
- Mouth position
- superior
- Distinctive features
- Series of dark, 'porthole-like' spots along the lateral line, Slender, somewhat translucent body, Males possess a gonopodium for internal fertilization
- Dorsal fin
- Single dorsal fin, typically positioned towards the posterior half of the body.
- Tail fin
- Caudal fin is rounded to slightly truncate.
- Pectoral fin
- Pectoral fins are small and clear.
- Distinctive fins
- Males have a modified anal fin called a gonopodium, which is elongated and used for sperm transfer.
Identification Tips
Body Markings
Look for the characteristic row of dark, often somewhat rectangular or oval, spots along the mid-flank, resembling portholes. This is the most reliable distinguishing feature.
Body Shape and Size
It is a small, slender fish, typically not exceeding 5 cm (2 inches) in total length. Its body is more elongated and less robust than many other livebearers.
Mouth Position
The mouth is superior (upturned), indicating a surface-feeding habit, which is consistent with its diet of small invertebrates and algae from the water surface.
Male Gonopodium
Adult males can be identified by their elongated, modified anal fin (gonopodium), used for reproduction.
Habitat
- Water type
- freshwater
- Depth
- Typically found in shallow waters, often near the surface.
- Environment
- Inhabits slow-moving to moderately flowing rivers, streams, canals, ditches, and ponds. Prefers areas with dense aquatic vegetation, submerged roots, and leaf litter, which provide cover and foraging opportunities. Can tolerate a range of water conditions but thrives in clear, well-oxygenated environments.
- Geographic range
- Native to Central America, specifically from southern Mexico (Veracruz, Oaxaca, Chiapas) south through Guatemala, Belize, Honduras, El Salvador, Nicaragua, and Costa Rica.
Aquarium Information
- Care level: beginner
- Temperament: peaceful
- Diet: omnivore
- Minimum tank size: 10 gallons (38 liters)
- Temperature: 22-28°C (72-82°F)
- pH level: 7.0-8.0
- Hardness: 10-25 dGH
- Compatibility: Excellent for community tanks with other small, peaceful fish. Avoid housing with aggressive or fin-nipping species.
- Special requirements: Requires clean, well-oxygenated water with some vegetation for cover and a dark substrate to enhance coloration. Can be sensitive to sudden changes in water parameters.
Wild Information
- Conservation status: least concern
- Seasonality: Breeds year-round in suitable conditions, with peak activity often coinciding with warmer, rainy seasons in its natural habitat.
- Market price: Low
- Commercial importance: low
- Taste: Not typically consumed due to small size.
- Texture: Not typically consumed due to small size.
- Nutritional value: Not typically consumed due to small size.
Key Facts
Viviparous Reproductionbehavior
Like all livebearers, Poeciliopsis gracilis gives birth to fully formed, free-swimming young, rather than laying eggs. This reproductive strategy offers a survival advantage in many environments.
Ecological Roleinteresting
Porthole Livebearers play a role in controlling insect populations, particularly mosquito larvae, and serve as a food source for larger fish and aquatic predators.
Sexual Dimorphismbehavior
Males are typically smaller and more slender than females, and possess a distinct gonopodium, making sex identification relatively easy.
Hardy and Adaptableinteresting
This species is known for its adaptability to various freshwater conditions, contributing to its wide distribution across Central America.
Safety Information
Safe- Safety level: safe
- Venomous: No
- Edibility: not recommended
- Handling notes: No specific handling precautions are required beyond standard care for small aquarium fish. Avoid excessive stress during capture or transfer.
Similar Species
Mosquitofish
Gambusia affinis
Gambusia affinis typically has a more robust body, a less distinct pattern of spots (often a single dark spot on the caudal peduncle), and a more aggressive temperament. Poeciliopsis gracilis is generally more slender and has the distinct 'porthole' markings.
Other Poeciliopsis species
Various Poeciliopsis spp.
Different Poeciliopsis species can be very similar. P. gracilis is distinguished by its specific pattern of lateral spots. Detailed examination of fin ray counts, body proportions, and gonopodial structure may be necessary for definitive identification among closely related species, especially in areas of sympatry.
Scientific Classification
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Actinopterygii
- Order
- Cyprinodontiformes
- Family
- Poeciliidae
- Genus
- Poeciliopsis
- Species
- Poeciliopsis gracilis
Explore Porthole Livebearer
Identify fish anywhere
Free on iOS, Android, and Web. Photo identification, full species details, and more.