Should I buy it?
Silver dollar
Metynnis argenteus
Also known as: green silver dollar (regional / trade line)
A schooling herbivore that eats every plant in the tank. Needs real lateral space and is incompatible with any planted aquascape.
Silver dollar tank mates · 300L tank size hub
peaceful · intermediate care
Sources & confidencehigh · partially verified · beginner: caution
Checked against several solid care sources that mostly agree. Numbers here are a careful starting point. Your tap water, tank size, and habits decide the rest. How we evaluate.
Best for: South American cichlid setups 300L or more with artificial plants or hardy plastic decor and a school of five or more.
Avoid if: You have a planted tank. Silver dollars methodically strip live plants within days.
Common mistakeAdding silver dollars to a planted community is how keepers invent a bare hardscape within forty-eight hours. Every stem and rosette gets eaten. Plan a plant-free or tough-only layout and a 300L-class school tank — not a show aquascape with 'just one dollar for interest.'
Top things that go wrong
- Shrimp & snails. Cherry shrimp and other dwarfs can coexist with peaceful small fish; baby shrimp are food for almost anything that finds them.
What most shops don't tell you
- 1.Myth: silver dollars are peaceful planted-community dither that leave aquascapes alone. Reality: they are dedicated plant eaters in a school that needs hundreds of litres — put them in planted show tanks and the plants lose within days, every time.
- 2.Predation risk scales with gape, night feeding, and crowding. 'they grew up together' is a schedule, not a law.
- 3.Classed peaceful for similar-sized community use. Still a bite-sized risk toward fry or very small comm fish in small volumes.
- 4.Bought as a 5 cm 'plant cleaner' for a 120 L general community for life.
- 5.Housed with long-finned guppies in small volumes. They nip and outcompete at the surface.
- 6.Veg and fibre matter long term. Pair with other large peaceful fast swimmers and real volume; 300 L class or more for a group of adults in most cases.
About this species
Silver dollars are deep-bodied South American characins that grow to 10 to 14 cm. Mostly herbivorous in the hobby, they still snap up anything that fits in an adult mouth. They are not a 100 L community fish at adult size.
- Banded leporinus300L min · same group, comparable tank size
- Denison's / red-line torpedo barb250L min · same group, comparable tank size
- Giant danio200L min · same group, similar adult size
- Rainbow / red-tailed black shark200L min · same group, similar adult size
- Rosy Barb180L min · same group, similar adult size
- Scissortail Rasbora150L min · same group, similar adult size
- Gold / Chinese barb120L min · same fish family
- Odessa Barb120L min · same group, similar adult size
- African freshwater butterflyfishalso intermediate peaceful, similar tank size
- Boesemani Rainbowfishalso intermediate peaceful, similar tank size
- Clown Loachalso intermediate peaceful, similar tank size
- Congo Tetraalso intermediate peaceful, similar tank size
- Cuckoo / petricola catfishalso intermediate peaceful, similar tank size
- Denison's / red-line torpedo barbalso intermediate peaceful, similar tank size
No reverse lookups listed yet.
Plan grid
Key limits are above. Here: pH band, swim level, bioload, and activity.
Swim zones
Care snapshot
Quick compare before you buy. Not a score of how “good” the fish is.
- Beginner ease22
- Peacefulness90
- Community fit76
- Small-tank fit76
- Hardiness54
- Energy86
Numbers are deterministic planning indices from Fishori fields — not a scientific score of your individual fish.
Example setups
Starting points only. Run the pair checker for every fish you add.
Match temperature and pH overlap with every tank mate, then verify adult size and group rules on pair pages — Fishori is biased toward boring, survivable plans.
Compatibility
Tank mates for Silver dollar
Usually safer (engine GOOD): Bala / silver shark, Tinfoil barb. Conditional (CAUTION — read the pair page before buying): Boesemani Rainbowfish, Chili Rasbora, Corydoras Catfish, Ember Tetra, Giant danio. Every name links to a live pair check — the lists are a shortlist, not a stocking plan.
Usually safer
Open a pair page with this fish as the starting point.
Needs planning
Read the blocking rule on each pair page before experimenting.
Usually avoid
Do-not-stock combinations on conservative hobby rules.
None listed. Use the pair checker before mixing.
Compare with
Run a real pair check: Silver dollar + Bala / silver shark
Behaviour and temperament
Silver dollars are peaceful with similar-sized active fish when given a real school and swim length. They are not aggressive hunters of robust tank mates, but fry and tiny fish can still be mouth-sized risk. Stress shows as pacing and fading when under-grouped in a short tank.
What sets them off
- Sudden crowding
- Poor water quality
Fin nipping: Not a habitual fin-nipper; stressed or crowded individuals can still test fins.
Predation: Not a predator toward similarly sized community fish; fry and dwarf shrimp are still fair game for most species.
Territory: Not strongly territorial, but still needs room so its working space does not overlap the next fish.
Planted tanks: caution — pick tougher plants
In the glass: typical and warning signs
- Five or more cruise midwater in a long open tank, flashing silver flanks.
- Steady plant browsing is normal ownership — design the hardscape for it.
- Pacing in a short planted cube means footprint and plant plan both failed.
- A thin pair usually needs more of their own kind before a different pellet.
- Low listed malice toward similar-sized peaceful fish.
- Tiny nano fish and fry can still disappear as mouth-size risk in tight quarters.
- Remove soft plants the same week you add the school — hoping fails.
- Grow the school before adding another 'active' species to fix shyness.
Fish behaviour can vary between individuals and tank setups. Always observe new fish closely after introduction.
Water, food, and grouping
Hardness
soft
Diet
herbivore
Silver dollars are midwater herbivores that take plant matter, blanched veg, and quality herbivore pellets in a school of five or more. Protein-heavy community flake alone leaves them thin and still hungry for your stems. Feed deliberately and expect every soft plant to be on the menu unless you keep a plant-free hardscape.
Shrimp & snails
Cherry shrimp and other dwarfs can coexist with peaceful small fish; baby shrimp are food for almost anything that finds them.
Schooling species — buy 5+ together. Smaller groups stress and lose colour.
- Hold 24 to 30 °C steadily on a real thermometer, not the dial on the heater.
- Aim for pH 5.5 to 7.5 and a hardness you can re-test in two weeks. A one-time strip in the shop car park is not a water test.
- Schooling species. Buy 5 or more from the same tank on the same day before adding any centrepiece fish.
- Tank volume meets or exceeds 300L published minimum for adults.
- You can stock at least 5 individuals (group welfare).
- Heater can hold 24–30°C without cooking cooler-water tank mates.
- No known fin-nippers paired with long-finned fish unless you accept documented risk.
Explore and stocking hubs
Tank-mates hub, matching guides, category peers, and litre stocking lists around this species’ minimum tank.
Plan with tools
Check mates as pairs first, then add this fish in the tank builder for the full stocking.
Filtration & heating
A 300L minimum tank needs a filter rated for at least 1200L/hr turnover and a heater to hold 24–30°C reliably.
Research: partially verified · Confidence: high · 3 linked source(s). We do not invent citations.
How Fishori evaluates compatibility (same logic as pair and tank tools).
- Seriously Fish. Metynnis argenteus
Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).
- FishBase. Metynnis argenteus
Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.
- Wikipedia. Metynnis argenteus
Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.
Evidence notes
- The Seriously Fish profile for the binomial in this record was successfully reached as the primary aquarium reference.
- FishBase contributes natural-range size and habitat context. Translate those numbers through your heater, your water report, and your tank footprint before stocking.
- Wikipedia is only cited if the article URL returned OK. Use it for orientation, not as the only care sheet for an import.
- All compatibility text reflects typical hobby experience and the Fishori model. Individual fish, shop stress, and the order tank mates are added in can still defy a single-paragraph label.
Common questions about Silver dollar
- How big do Silver dollar get?
- Silver dollar adults run about 10–14 cm. In home tanks they usually land near 12 cm — plan space and filtration for that, not the juvenile in the shop bag.
- What size tank does Silver dollar need?
- 300L is the planning floor for adult swimming space and bioload. A 400L+ tank is the more comfortable long-term footprint. Length and depth matter as much as raw litres for active or territorial fish.
- Are Silver dollar aggressive?
- Silver dollars are peaceful with similar-sized active fish when given a real school and swim length. They are not aggressive hunters of robust tank mates, but fry and tiny fish can still be mouth-sized risk. Stress shows as pacing and fading when under-grouped in a short tank.
- Do Silver dollar need to be kept in a group?
- Schooling species — buy 5+ together. Smaller groups stress and lose colour.
- What is the most common mistake with Silver dollar?
- Adding silver dollars to a planted community is how keepers invent a bare hardscape within forty-eight hours. Every stem and rosette gets eaten. Plan a plant-free or tough-only layout and a 300L-class school tank — not a show aquascape with 'just one dollar for interest.'
- What fish can live with Silver dollar?
- The Silver dollar profile lists Bala / silver shark, Tinfoil barb among its safer pairings (engine-checked GOOD). Boesemani Rainbowfish, Chili Rasbora, Corydoras Catfish, Ember Tetra are conditional (CAUTION): workable only with the specific conditions on each pair page. Run the pair checker for your exact water and tank size before stocking.