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FishmediumFreshwater

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.

Size6"
Min Tank75g
School5+
peaceful
Zonemiddle

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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.

Common Diseases

Ich (White Spot Disease)

Symptoms

Small white spots resembling grains of salt covering the body and fins, flashing against surfaces, lethargy, and loss of appetite

Treatment

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)

Symptoms

Pitting or erosion of the sensory pores on the head and lateral line, mucus trails from lesions, loss of color, and reduced appetite

Treatment

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

Symptoms

Swollen abdomen, raised or pinecone-like scales, lethargy, loss of appetite, and buoyancy issues

Treatment

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

Symptoms

Fraying, discoloration, or deterioration of fins, often with a white or red edge at the affected area

Treatment

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)

Stats

Community tips0
Kept by0 hobbyists