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Girardinus metallicus



    A freshwater/brackish cyprinid that’s at home in a peaceful, livebearer community tank. Males appear to have metallic silver diamonds inset into the soft gold of their flanks and are underlined in black from their chins to their caudal peduncles.

Quick stats:

Listed tank sizes are the minimum
Size: Adult male: up to 2.0 inches (5.0 cm) Adult female: 3.5 inches (9.0 cm)
Tank: School of 3-4: 20 gallons (75.7 liters) or larger School of 6-8: 55 gallons (208.20 liters) or larger
Strata: Top to Middle
PH: 6.0-8.0
Hardness: Medium, dH: 9.0-19.0
Temperature: 72 – 77°F (22 – 25°C)


Order: Cyprinodontiformes
Family: Poeciliidae
Genera: Girardinus
Species: Girardinus metallicus

Common name:


Metallic Livebearer

    , Metallic Topminnow


Central America: Costa Rica, Cuba. Occurs in clear, slow-flowing or still water ditches, lakes, ponds and streams.

General Body Form:Streamlined head and body. Dorsal, pectoral, and caudal fins are medium length and rounded. Mouth is superior. Females have longer, deeper, more rounded bodies with rounded anal fins. Males have smaller, shorter, more laterally compressed bodies with a long, pointed gonopodium.

Coloration:Bodies and heads range between translucent silver, pale gold or olive. Iridescent silver diamond-shaped bars along the lateral line. Dorsal fin has a black spot at the bottom center of the dorsal fin. Males have a deep overall metallic gold sheen, making the silver diamonds appear brighter and larger than on the paler female. Males faces feature black blotches and their mouths and undersides of their chins, chests, stomachs, gonopodiums and tails are lined in black.


  • Care:
  • Water:
    Brackish, Fresh. The Central American waters these fish hail from are brackish, although they have also been successfully kept in freshwater. To create mildly brackish water, you’ll need a hydrometer and marine salt. Add 2 tablespoons of marine salt per gallon of water, increasing your salinity by 1 extra tablespoon per gallon every six months. It may take several years to reach a salinity of 1.020-1.025, but increasing salinity gradually is safest for your fish. Pay special attention to your hydrometer during water changes to ensure the salinity stays within a safe range.
  • Diet:
    Omnivorus: Enjoys live or frozen brine shrimp, larvae and daphnia, algae flakes and small pelleted foods.
  • Tank/Decor::
    A Central American river biotope can be replicated in a medium-sized tank with sand or gravel substrate. Water should be calm, clear and well-oxygenated. Plant densely, including a few floating plants to help dapple the light. Rocks, driftwood, and sticks help provide hiding places.
  • Communities:
    Ideal community fish, lives in hierarchic schools. Keep in a 1 male to 3 females ratio. Excellent tankmates include: anableps, bettas, bumblebee gobies, corydoras, danios, guppies, mollys, platys, rainbowfish, swords and tetras.


    Tropical rainforest streams, ponds and swamps.

Breeding:Easy—Prolific. Sexual dimorphism: Males have a large tubular anal fin called a gonopodium. Dominant males are smaller than others and generally have brighter colors. Submissive males are slightly larger and not as colorful. Mature females are fuller-bodied, larger and have muted colors. Males inseminate females using their gonopodium. After she is inseminated, a dark gravid spot appears at the base of the female’s anal fin. Typically in the morning of the 28th day roughly 5 to 30 fry are born over the course of an hour. Females can store sperm for up to a year and can have fry every 28 days, even without the presence of a male. Fry must either have baby grass to escape into or must be removed to avoid predation by adults. Feed crushed flake food, brine shrimp nauplii, cooked egg yolk and spirulina for robust growth. Fry are sexually mature within 3 to 8 weeks.







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