Silver Dollar (Metynnis argenteus) | Live Freshwater Community Fish

The Silver Dollar (Metynnis argenteus) is a peaceful, beginner-friendly schooling fish from the Amazon Basin — and one of the most rewarding "big fish" you can keep in a community tank. Closely related to piranhas but with a thoroughly herbivore diet, Silver Dollars cruise in tight schools through the middle and upper water column, their bright silver bodies catching every flicker of light. They thrive in larger tanks with similarly-sized peaceful tank mates. See more of our freshwater livestock and supplies.

Care Guide

Silver Dollars are hardy and forgiving once their basic needs are met. The non-negotiables: a large tank (75 gallons minimum for a school of 5–6 adults), a school of at least 5 — they get extremely stressed alone or in pairs — and a vegetable-heavy diet. They are voracious herbivores and will demolish most live plants, so plan on tough plants like Anubias and Java Fern tied to driftwood, or use silk/plastic décor. Provide open swimming space across the tank; they're fast and need room to school.

Soft, slightly acidic to neutral water mirrors their Amazonian origin, but they tolerate a wide range. Strong filtration is important — these are messy eaters — and weekly 25% water changes keep them in top color and health.

Specifications

Compatibility

Best tank mates: larger peaceful community fish that won't be confused for food. Good matches include angelfish, larger gouramis, peaceful cichlids, plecos, larger catfish, and bottom-dwellers like cory cats in groups.

Avoid: very small fish (neon tetras, guppies, ember tetras) that fit in their mouth, fin-nippers (tiger barbs), and aggressive cichlids. Also avoid prized live-planted tanks — Silver Dollars will sample everything green.

Recommended Foods & Supplies

• Seachem NutriDiet Herbivore Tabs — sinking herbivore staple, ideal for Silver Dollars.
• Seachem Prime — essential water conditioner for water changes.
• Cholla Wood — natural driftwood that gently softens water and looks at home in an Amazon biotope.
• Blanched zucchini, cucumber, and spinach — Silver Dollar favorite treats.
• Browse all aquarium foods — pellets, flakes, wafers, and more.

FAQ

Do I really need a 75-gallon tank?
Yes. Silver Dollars get 4–6 inches and need a school of 5+ to feel secure. A 75-gallon is the practical minimum for the footprint and water volume; a 90 or 125 gallon is even better for a long-lived, full-grown school.

Will they really eat my plants?
Almost certainly. Silver Dollars are voracious herbivores. The only live plants that reliably survive are tough, low-palatability species like Anubias, Java Fern, and Bolbitis — and even those can get nibbled. Most keepers use silk/plastic décor or focus on driftwood and hardscape.

Are they really related to piranhas?
Yes, they share the family Serrasalmidae — but unlike piranhas they are dedicated herbivores with no aggressive tendencies toward tank mates. Think of them as the gentle cousin.

Can I keep just one or two?
Please don't. Silver Dollars are obligate schooling fish — kept alone or in pairs they become stressed, skittish, and prone to disease. Always buy in groups of 5 or more.

Are they jumpers?
Yes, especially when startled. A tight-fitting lid is required.