Silver Dollar (Metynnis Hypsauchen)

The Silver Dollar is a shimmering, metallic fish native to the Amazon River basin. Its body is nearly circular and laterally compressed (very thin), looking exactly like a large silver coin swimming through the water. While they are peaceful, they are very active and can be quite skittish. Their most famous trait is their herbivorous appetite; in a planted tank, they act like a "lawnmower," making them one of the few fish that can actually be a challenge for an aquascaper.

Key Information

• Common Name: Silver Dollar

• Scientific Name: Metynnis hypsauchen (often confused with M. argenteus)

• Origin: South America (Amazon and Paraguay River basins)

• Max Size: 15 cm

• Lifespan: 10+ years

• Temperament: Peaceful but skittish

• Diet: Herbivore – Loves spirulina flakes, vegetable wafers, blanched spinach, and cucumber.

• Care Level: Easy to Moderate

Water Parameters

Parameter	Value
Temperature:	24–28°C
pH:	6.0–7.0
Hardness:	4–15 dGH
Minimum Tank Size:	285L+ (75 Gallons) for a school

Behaviour & Tank Compatibility

Silver Dollars are strictly schooling fish and should be kept in a group of at least 5–6 specimens. When kept alone, they become extremely stressed and may injure themselves by darting into the glass.

They are excellent tank mates for large, semi-aggressive fish because they are fast and deep-bodied enough to not be bothered. They pair perfectly with Oscars, Neon Blue Acaras, and large Catfish.

Warning: They will eat almost any live plant in the aquarium. If you want greenery, you must stick to very tough plants like Java Fern or Anubias, or use silk/plastic plants.

Ideal Tank Setup

• Swimming Space: They are powerful, fast swimmers. An open middle area in a long tank is essential.

• Secure Lid: Absolute Necessity. Silver Dollars are notorious for jumping when startled (e.g., when the room lights are turned on suddenly).

• Dark Background: This helps the fish feel more secure and makes their silver scales "pop" visually.

• Visual Barriers: Driftwood and large rocks should be placed around the edges to give them places to retreat if they feel threatened.