Should I buy it?
Silver dollar
Metynnis argenteus
Also known as: green silver dollar (regional / trade line), Green silver dollar (regional / trade line)
Fishori provides conservative planning guidance, not guarantees.
Based on multiple reputable aquarium care sources with strong agreement. Use the numbers here as planning defaults — your room, water, and routine still shape real-world outcomes.
A schooling herbivore that eats every plant in the tank. Needs real lateral space and is incompatible with any planted aquascape.
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.
Top things that go wrong
- Mouth gap vs tiny tank mates. Predation risk toward smaller tank mates. The figure that matters is the adult mouth size against the adult prey length, not the juvenile sizes in the shop.
- Shrimp & snails. Shrimp: not safe. The fish will eat adult shrimp, shrimp fry, or both, depending on the size of the shrimp.
Common mistakeSilver dollars in a planted community. Every stem plant and rosette will be consumed within 48 hours of introduction.
What most shops don't tell you
- 1.Predation risk scales with gape, night feeding, and crowding. 'they grew up together' is a schedule, not a law.
- 2.Classed peaceful for similar-sized community use. Still a bite-sized risk toward fry or very small comm fish in small volumes.
- 3.Bought as a 5 cm 'plant cleaner' for a 120 L general community for life.
- 4.Housed with long-finned guppies in small volumes. They nip and outcompete at the surface.
- 5.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
- Denisons 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
- 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 on file yet.
Plan grid
Key limits are shown above; this section adds planning detail: pH band, swim level, bioload and activity, and the radar.
Swim zones
Planning trait chart
Six indices for comparing species on paper before you spend.
- Beginner ease22
- Peacefulness76
- Community fit73
- Small-tank fit76
- Hardiness54
- Energy86
Numbers are deterministic planning indices from Fishori fields — not a scientific score of your individual fish.
Common setup sketches
Conservative patterns from Fishori fields — still run the pair checker for every species you add; sketches are not a stocking guarantee.
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.
Tank mate intelligence
Use the "Often compatible" lists as a shortlist, not a stocking plan. Always run the pair tool and check the footprint of your actual tank first. Verify behaviour for Silver dollar against your own reading before you buy.
Pair-level compatibility with this fish as anchor.
Read the blocking rule on each pair page before experimenting.
Do-not-stock combinations on conservative hobby rules.
Compare with
Run a real pair check: Silver dollar + Boesemani Rainbowfish
Behaviour, temperament, and what to watch
Prose and lists come from the same record: read temperament first, then glass-level signals so you are not surprised after day three.
Silver dollar is peaceful in mixed company. Treats any fish small enough to fit in its mouth as food. Mouth size at adult length matters, not the prey's listed adult size.
Stress / aggression triggers on file
- Sudden crowding
- Poor water quality
Fin nipping: Not a habitual fin-nipper, but individuals can still test fins under stress or in a crowded tank.
Predation: Predation risk toward smaller tank mates. The figure that matters is the adult mouth size against the adult prey length, not the juvenile sizes in the shop.
Territory: Not strongly territorial, but still claims a working area in the tank. Give it room to settle without overlapping the next species' patch.
Planted tanks: caution — pick tougher plants
In the glass: typical and warning signs
- Busy at feeding time — expects food to hit the water predictably.
- Shoaling/schooling: most colour and confidence show when the group meets **5+**.
- Clamped fins, gasping at the surface, hiding non-stop, or refusing food after the first week.
- Rapid breathing when parameters swing — fix ammonia/nitrite first, then reassess mates.
- Low listed risk — still watch new introductions.
- Separate or rehome if injuries appear, one fish is pinned, or feeding becomes a daily chase.
- If water is stable but behaviour worsens, reduce stocking or remove the highest-impact species first.
Fish behaviour can vary between individuals and tank setups. Always observe new fish closely after introduction.
Care parameters: water, food, inverts, grouping
Chemistry and group rules sit here so you are not re-reading the same line from tank mate or temperament blocks. Swim level is in the plan grid above.
Hardness
soft
Diet
herbivore
Vegetable matter, algae, and plant-based prepared foods. Long-term protein-only feeding causes bloat in herbivorous species.
Shrimp & snails
Shrimp: not safe. The fish will eat adult shrimp, shrimp fry, or both, depending on the size of the shrimp.
Shoaling species. Buy 5 or more of one species together. Smaller schools sulk, lose colour, and redirect their schooling energy at whatever else is in the tank.
Egg scatterers and schoolers still spawn in stable tanks. Have a plan for the fry, or accept that the parents and tank mates will eat them in a community setup.
- 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.
- No tank mates small enough to fit the adult mouth gap for this species.
Explore and stocking hubs
Same library as the rest of Fishori: tank-mate index for this species, category peers, guides, and litre-based stocking lists where min tank on file is within the hub volume.
Plan with tools
Pair-level rules and multi-fish stocking use the same conservative engine — add this fish in the tank builder only after mates pass pair checks.
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.
Profile status: partially verified · Evidence tier: high · 3 linked source(s). Fishori does not fabricate citations.
Fishori uses conservative planning rules based on these sources.
Confidence is explained in the summary at the top of this page (same tier as here), not repeated below.
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.
- Fishori profiles work from typical aquarium trade sizes and hobby care norms. Specialist site checks and literature review for this species are not yet recorded here, so the ranges on this page are planning numbers rather than guarantees.