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Spotted Silver Dollar
Metynnis maculatus
📍 South America
The Spotted Silver Dollar (Metynnis maculatus) is a striking, disc-shaped characin native to South American river systems, recognized by its silvery body adorned with small dark spots. It is a popular choice for large community aquariums due to its peaceful nature and schooling behavior. Hobbyists should be aware of its strong herbivorous tendencies, which can quickly decimate live plants in the aquarium.
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Care Guide
Diet
Spotted Silver Dollars are predominantly herbivores and should be fed a diet rich in plant-based foods such as blanched zucchini, spinach, romaine lettuce, spirulina flakes, and herbivore pellets. They will also accept high-quality flake foods and occasional fruit pieces as treats. Feed 2-3 times daily in amounts they can consume within a few minutes, and avoid keeping them with prized live plants as they will eat most soft-leaved species.
Behavior
Spotted Silver Dollars are active, schooling fish that feel most secure and display their best behavior when kept in groups of five or more. They are generally peaceful toward similarly sized tankmates but may nip at the fins of slow-moving or long-finned fish. They tend to be somewhat skittish and appreciate a well-planted tank with open swimming areas, though artificial or robust plants are recommended given their herbivorous nature.
Breeding
Breeding Spotted Silver Dollars in captivity is achievable but requires a large, dedicated breeding tank with soft, acidic water and dim lighting. They are egg scatterers, releasing hundreds of eggs among fine-leaved plants or spawning mops, after which the parents should be removed to prevent egg predation. The eggs typically hatch within 3 days, and the fry are initially fed infusoria or finely crushed spirulina before transitioning to baby brine shrimp.
Tank Mates
Congeneric species that shares similar size, temperament, and water requirements; schools well together
Similar body shape and peaceful temperament; thrives in the same water conditions and large schools
Large, peaceful South American species that coexists well in spacious tanks with similar water parameters
Peaceful, similarly sized schooling fish from comparable water conditions; both need large tanks
Peaceful cichlid of similar size that shares South American origins and compatible water parameters
Bottom-dwelling algae eater that occupies a different zone and poses no threat to silver dollars
Common Diseases
Ich (White Spot Disease)
Small white spots resembling grains of salt covering the body and fins, flashing against surfaces, lethargy, and loss of appetite
Gradually raise water temperature to 30°C (86°F) and treat with an ich-specific medication such as malachite green or formalin-based products; perform frequent water changes during treatment
Hole-in-the-Head Disease (HITH)
Pitting or erosion of the sensory pores on the head and lateral line, mucus trails from lesions, loss of color, and reduced appetite
Improve water quality with frequent water changes, reduce activated carbon use, supplement diet with vitamins, and treat with metronidazole if bacterial or parasitic infection is confirmed
Dropsy
Swollen abdomen, raised or pinecone-like scales, lethargy, loss of appetite, and buoyancy issues
Isolate affected fish, improve water quality, and treat with a broad-spectrum antibiotic such as kanamycin or trimethoprim-sulfamethoxazole; prognosis is often poor if caught late
Fin Rot
Fraying, discoloration, or deterioration of fins, often with a white or red edge at the affected area
Improve water quality through regular water changes, remove any aggressive tankmates, and treat with antibacterial medications such as kanamycin or erythromycin
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Quick Facts
- diet
- Herbivore – primarily plant matter including blanched vegetables, spirulina, and aquatic vegetation; will accept some prepared foods
- lifespan
- 8-12 years
- max size
- 15 cm (6 in)
- tank size
- 75 gallons minimum
- temperament
- peaceful
Water it likes
- ph
- 5.5-7.5
- ammonia
- 0 ppm
- nitrate
- <20 ppm
- hardness
- 4-15 dGH
- temperature
- 75–82°F (24–28°C)