Tiger Silver Dollar 'Rio Capim' (Metynnis fasciatus)

Common Name

Tiger Silver Dollar
Metynnis fasciatus

The Tiger Silver Dollar is a beautifully patterned Metynnis known for its bold vertical bars and reflective silver body. It offers the classic silver dollar look with extra contrast and color that makes a school of them stand out in large freshwater aquariums.

Origin and Habitat

Tiger Silver Dollars are native to the eastern and central Amazon basin of Brazil. They were originally described from the Capiuru River drainage. More recent distribution includes clearwater tributaries of the Araguaia, Tocantins, Xingu, and Tapajós systems.

These rivers contain warm, soft, slightly acidic clearwater flowing over sandy and rocky substrates. Seasonal floods bring fruits, seeds, leaves, and plant matter into the water. Schooling Metynnis species occupy margins, slow channels, and oxbow lakes.

Fish commonly found with Metynnis fasciatus include:

• Bryconops species
• Moenkhausia and Astyanax tetras
• Geophagus and Satanoperca cichlids
• small Amazonian catfish

Temperature and Water Conditions

• Temperature: 24–28 °C (75–82 °F)
• Wild pH: 6.0–6.8
• Aquarium pH: 6.3–7.5
• Hardness: soft to moderately hard
• Ammonia & nitrite: 0 ppm
• Nitrate: keep very low

Stable conditions are far more important than chasing exact wild parameters. Strong filtration, good oxygenation, and steady temperature are required.

Appearance and Size

Tiger Silver Dollars have a tall disc-shaped body with reflective silver coloration marked by bold vertical bars. Under good lighting, green and blue iridescence may appear on the body, with warm orange or red tinting the fins.

Adults reach around 12–15 cm (4.7–5.9 in) in total length.

Diet in the Wild

Metynnis species are herbivores and frugivores that graze on plant matter, fallen fruits, seeds, leaves, algae, and small invertebrates found in flooded forest and clearwater tributaries.

Feeding in Captivity

• Staple: spirulina-based flakes or pellets
• Regular supplements: algae wafers and vegetables (spinach, romaine, zucchini, peas, cucumber)
• Occasional protein: brine shrimp, bloodworms, or daphnia once or twice weekly

Behavior and Tank Setup

• Keep in groups of 6 or more
• Minimum tank for small group: 75–90 gallons
• Larger groups: tank at least 150 cm (5 ft) long
• Provide open swimming space + driftwood/roots along the edges
• Strong filtration and a tight-fitting lid are essential

Suitable tank mates include larger tetras, rainbowfish, peaceful Geophagus, and medium-sized catfish.

Breeding

Tiger Silver Dollars are open-water egg scatterers. They spawn among plants or spawning mops. Warm water (26–28 °C) helps trigger spawning.

• Eggs hatch in 2–3 days
• Fry start on infusoria, then move to newly hatched brine shrimp

Quick Facts

• Scientific name: Metynnis fasciatus
• Common name: Tiger Silver Dollar
• Origin: Capiuru River drainage and clearwater tributaries of the Araguaia, Tocantins, Xingu, and Tapajós systems
• Adult size: 12–15 cm (4.7–5.9 in)
• Temperature: 24–28 °C (75–82 °F)
• pH: 6.0–6.8 in the wild (keep stable in aquarium)
• Hardness: soft to moderately hard
• Temperament: peaceful schooling fish
• Diet: primarily herbivorous while eating small invertebrates
• Breeding: open-water egg scatterer

Tropical Fish Co. Notes

Tiger Silver Dollars give people something special compared to the common silver dollar. Their bold bars and warm fin tones create a moving centerpiece in large aquariums.

Jonny has always been a silver dollar guy, so adding this species was something he was really looking forward to. The strong barring and reflective finish are exactly the traits he loves showing people. It is one of the silver dollars he is most excited to feature.

These fish also make excellent dither fish for peaceful South American cichlids. A plant-based diet keeps them healthy, colorful, and active.