A large, peaceful schooling characin renowned for its laterally compressed, coin-like silver body. They are notorious herbivores that will devour almost any live plant in the aquarium. Highly skittish, they are known to dart rapidly when startled, requiring ample unobstructed swimming space and a tight-fitting lid.
At a Glance
Tank Requirements
Water Parameters
Temperament & Compatibility
Available Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Standard
The standard silver dollar seen in the trade. Must be kept in groups of 5 or more to prevent panic and stress. Best kept in a hardscape-only aquarium (driftwood and smooth rocks) as they will eat live plants down to the stems.
Same care requirements as the base species
Also known as: Common Silver Dollar
Silver Dollar Care Summary
The Silver Dollar, scientifically known as Metynnis argenteus, belongs to the Characins family group. Adults reach a maximum size of approximately 15 cm and have a compressed body shape with a fast growth rate. Classified as peaceful, this species primarily occupies the mid-level and surface zones of the aquarium and produces a high level of biological waste.
To thrive, the Silver Dollar requires a freshwater only aquarium with a minimum volume of 280 litres and a tank length of at least 120 cm. Water temperature should be maintained between 24°C and 28°C, with a pH range of 5.5–7.5 and a general hardness of 4–15 dGH. A moderate water flow is preferred. To replicate their natural habitat, the tank should include driftwood (digestion/hiding) and smooth gravel (sensitive barbels).
This species should be kept in groups of at least 5 to reduce stress and encourage natural behaviour. Keepers should be aware that this species may uproot or eat live plants and is a known jumper, so a tight-fitting lid is essential. The Silver Dollar is typically available in one standard form.
Similar Species
Rummy-Nose Tetra
Hemigrammus rhodostomus
Renowned as the tightest schooling fish in the freshwater hobby. They feature a bright red nose, a silver body, and a black-and-white checkered tail. They are excellent 'indicator fish'; their red noses will fade to pale pink if water quality drops or the fish are stressed. While there are three very similar species (H. rhodostomus, H. bleheri, P. georgiae) often sold under the same name, their care requirements are identical.
Silver Arowana
Osteoglossum bicirrhosum
A massive, prehistoric-looking surface predator native to the Amazon Basin. Known for their metallic silver scales and incredible jumping ability (used in the wild to catch insects from low-hanging branches). They grow exceptionally fast and require gigantic aquariums. They will consume any tank mate small enough to fit into their large, trapdoor-like mouths.
Scarlet Badis
Dario dario
One of the smallest known aquarium fish, resembling a tiny jewel. Males display brilliant vertical red and iridescent blue stripes. While beautiful, they are known for being extremely picky eaters, often refusing dry foods and requiring live or frozen micro-foods (Daphnia, Baby Brine Shrimp). Males act like tiny Cichlids and will stake out territories.
Bronze Corydoras
Corydoras aeneus
A highly popular, peaceful schooling catfish known for its armor-like scales (scutes) and active bottom-feeding behavior. They are essential clean-up crew members but require a dedicated sinking diet (not just leftovers). Sand substrate is strictly required to prevent erosion and infection of their sensitive barbels. They are 'gut breathers' and will occasionally dart to the surface to gulp atmospheric air.
Siamese Algae Eater
Crossocheilus oblongus
Famous for being one of the few freshwater fish that actively consumes Black Beard Algae (BBA). A torpedo-shaped, active bottom-to-midwater swimmer native to Southeast Asian streams. True Siamese Algae Eaters feature a distinct black horizontal stripe that extends all the way through the tail fin. As they mature, they can become lazy, preferring prepared foods over algae, and may occasionally chase other bottom dwellers.
Betta (Siamese Fighting Fish)
Betta splendens
The Siamese Fighting Fish is an aquarium icon known for its labyrinth organ (allowing air breathing) and vivid colors. While hardy, they require heated, filtered water (24-30°C). Males are solitary and fiercely territorial. Females are generally less ornate but can be kept in 'sororities' with strict precautions (minimum 5 females in 75L+).