Silver Dollar (Metynnis) Care Guide
Metynnis hypsauchen is a round, peaceful schooling characin from South America, a herbivorous relative of piranhas that readily eats aquarium plants.
Compiled by Aquairi from published sources · Published · Updated
Overview
Metynnis hypsauchen, commonly called the silver dollar, is a round, laterally compressed characin in the family Serrasalmidae. Described by Müller and Troschel in 1844, it is a peaceful, herbivorous relative of piranhas and pacus, and is frequently confused with the similar Metynnis argenteus.
Taxonomy
- Family: Serrasalmidae
- Genus: Metynnis
- Scientific name: Metynnis hypsauchen
- Order: Characiformes
Habitat
The species occurs in the Amazon and Paraguay River basins and rivers of the Guiana Shield. FishBase classifies it as a tropical, pelagic freshwater fish of slightly acidic water.
Tank requirements
- Minimum tank volume: 300 L
- Temperature: 24-28 °C (75-82 °F)
- pH: 5.5-7.5
- GH: 4-18 °dGH
- School size: 5 or more individuals
- Lifespan: 8-12 years
Diet
Metynnis hypsauchen is primarily herbivorous, with FishBase recording a trophic level around 3.5 reflecting a mostly plant-based diet supplemented by some animal matter. It eats virtually all soft aquarium plants, so planted layouts are difficult to maintain with this fish.
Compatibility
This is a peaceful, middle-water schooling fish best kept in groups of five or more. Suitable companions include larger tetras and plecos; soft live plants are eaten and should be considered incompatible.
Conservation status
IUCN Red List: Least Concern.
Silver Dollar (Metynnis hypsauchen) Breeding Guide
Overview
Metynnis hypsauchen, a silver dollar, is a peaceful, largely herbivorous South American characin reaching about 15 cm. Seriously Fish describes it as a group spawner rated moderately difficult to breed. Wikipedia characterises the silver dollar as a benthic spawner and egg scatterer producing large clutches.
Sexing
According to Seriously Fish the anal fin is more elongated and more colourful on the male, and males develop darker coloration when ready to spawn, especially on the anal, caudal and dorsal fins, with intensified redness on the chest.
Conditioning
The species takes heavy vegetable matter such as courgette, cucumber, peas and greens, plus algae wafers, spirulina and vegetable flake, and will also accept bloodworm and brine shrimp. Well-fed groups develop spawning condition, with males pursuing females and performing shimmying displays.
Breeding Setup
Seriously Fish recommends the softer, more acidic end of the range, roughly pH 6.0-7.0 and hardness up to about 10 dH, with temperature around 28 C. Wikipedia adds that breeding water should be soft (around 8 dGH or below) and warm. A warmer water change can help trigger spawning.
Spawning Behavior & Trigger
Males pursue females and shimmy; females release eggs that males fertilise, and the eggs settle to the tank bottom. Seriously Fish reports as many as 2000 eggs per spawning pair, consistent with Wikipedia's figure of up to 2000 eggs.
Egg & Fry Care
Parents should be removed after spawning as they are not true guarders. Eggs hatch in around three days, and Wikipedia notes the fry are free-swimming after about a week. Seriously Fish advises starting fry on infusoria before progressing to newly hatched brine shrimp and powdered foods; high mortality is expected and culling of weak fry is recommended.
Common Challenges
Large adult size means a sizeable tank is required for a spawning group, and the very large clutch with high fry mortality demands abundant tiny first foods. As a herbivore, breeding stock will damage live plants in the setup.