Silver Dollar (Metynnis hypsauchen) Breeding Guide

Metynnis hypsauchen is a herbivorous group-spawning characin that scatters large clutches of eggs; this guide covers sexing, triggers and fry rearing.

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.