Spotted Dollar

fish description – Spotted Silver Dollar Care Guide ($Metynnis\ maculatus$)

Category	Detail
Scientific Name	$Metynnis\ maculatus$ (or $M.\ lippincottianus$)
Common Name	Spotted Silver Dollar, Spotted Metynnis
Origin	Amazon River Basin (Brazil, Peru, Colombia)
Adult Size	6–7 inches (15–18 cm)
Temperament	Peaceful, highly active, shy, easily startled
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 the classic, flat, coin-like body profile of the Silver Dollar, but its silvery body is adorned with numerous small, dark spots or blotches that vary in intensity. It is a highly active mid-water swimmer.
• Coloration: Iridescent silver or gray base color with scattered dark spots across the flanks. Males develop a slightly longer, often red-tinged anal fin with a black stripe, and their colors may darken during breeding displays. Females are rounder and larger-bodied.
• Fins: Proportional; the anal fin is a key feature for sexing.
• Behavior: A nervous and fast-swimming shoaling species that must be kept in groups to reduce stress and prevent it from darting into the glass. They are voracious herbivores and are known to jump when startled.

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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 for their darting movements.
• Schooling: Must be kept in schools of at least 5–6 individuals or more. Keeping fewer will make them timid and prone to panic.
• Temperature: Tropical range: $74^\circ$–$82^\circ\text{F}\ (23^\circ$–$28^\circ\mathrm{C})$.
• pH Level: Soft, neutral to slightly acidic water: 6.0 to 7.5. They require clean, well-oxygenated water with strong filtration and regular water changes (25% weekly).
• Aquascape: Requires vast open swimming space in the center. Do not use soft-leaved live plants; they will be eaten. Use artificial plants or extremely sturdy, tough-leaved plants (Anubias, Java Fern) tied to decor. 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 Spotted 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 (zucchini, cucumber, peas, spinach, lettuce). Meaty treats (bloodworms) should be rare and given sparingly.
• Schedule: Feed 2–3 times daily in small portions. Their constant appetite requires consistent feeding to prevent them from damaging or consuming 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 be eaten.
• 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).