Dollar

fish description – Silver Dollar Fish Care Guide ($Metynnis\ argenteus$)

Category	Detail
Scientific Name	$Metynnis\ argenteus$ (or $M.\ hypsauchen$)
Common Name	Silver Dollar Fish, Metynnis
Origin	Amazon and Paraguay River Basins (South America)
Adult Size	6–8 inches (15–20 cm)
Temperament	Peaceful, highly active, shy, prone to jumping
Lifespan	10+ years
Care Level	Intermediate (due to large tank requirement and diet)

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Appearance and Sexual Differences

 

• Short Description: This fish has a deep, round, and highly laterally compressed body that gives it a flat, coin-like profile. Its scales are brilliantly shimmering silver, sometimes with green or blue tints. Males often show red markings on the anal fin.
• Coloration: Entirely iridescent silver. Males develop a more elongated, reddish anal fin with a black stripe, and their colors may darken during courtship. Females are generally rounder and less colorful in the fins.
• Fins: The anal fin is often the most colorful part.
• Behavior: A nervous, fast-swimming shoaling species that must be kept in groups to feel secure; kept alone, it will be skittish and stressed. They are prone to jumping when startled and are voracious plant eaters.

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Tank Requirements and Water Parameters

 

• Minimum Tank Size: 75 gallons (284 liters) is the minimum for a school of 5–6 fish. A long tank is mandatory to provide adequate horizontal swimming space.
• Schooling: Must be kept in schools of at least 5–6 individuals or more. This reduces their skittishness and encourages natural schooling behavior.
• Temperature: Tropical range: $75^\circ$–$82^\circ\text{F}\ (24^\circ$–$28^\circ\mathrm{C})$.
• pH Level: Soft, neutral to slightly acidic water: 6.0 to 7.5 (wild types prefer lower $\text{pH}$). They require strong filtration and good oxygenation.
• Aquascape: Requires vast open swimming space in the center. Do not use soft-leaved live plants; they will be eaten. Use robust, unappetizing plants (e.g., Anubias or Java Fern tied to driftwood) or artificial plants. Provide secure hiding spots with rocks and driftwood on the periphery. A secure, heavy lid is essential.

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Diet and Feeding

 

The Silver Dollar is an herbivore that requires a fiber-rich, plant-heavy diet.

• Staple Diet: The diet should be predominantly vegetable matter. Offer high-quality vegetable flakes, spirulina pellets, and algae wafers as the staple.
• Supplementation: Must receive frequent servings of blanched fresh vegetables (spinach, zucchini, peas, lettuce). Offer meaty treats (bloodworms, brine shrimp) only occasionally and sparingly.
• Schedule: Feed 2–3 times daily in small portions. Their constant appetite requires consistent feeding to prevent them from damaging live plants.

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Compatibility

 

• Caution: Will devour most live plants. Can be skittish and their sudden darting movements may startle timid fish. They are generally peaceful but should not be kept with fish small enough to fit in their mouth.
• Good Tank Mates: Other large, peaceful, or semi-aggressive fish that are too big to be eaten. Examples include Severums, Angelfish (large adults), Firemouth Cichlids, Rainbowfish, Gouramis, and large Catfish (Plecos, Doradids).