Ctenobrycon spilurus
A peaceful, silvery characin ideal for planted community aquariums.
Ctenobrycon spilurus, called the silver tetra or silver dollar tetra, is a freshwater ray-finned fish in the family Acestrorhamphidae. It lives in the Orinoco River basin and coastal river basins of Guyana, Suriname, French Guiana, Brazil, and Venezuela, favoring shallow, slow-moving streams with thick vegetation. Water temperatures there range from 23–27 °C (73–81 °F). The fish reaches a maximum length of 8.0 cm (3+1⁄4 in).
Its body is round, flattened, and silvery-gray, sometimes with a slight olive green tint. A black patch appears at the base of the caudal fin, and some individuals have a small dark spot near the gill covers. Males show a red glow in the rear part of the anal fin. The dorsal fin is short, and the mouth is small with enlarged lips.
In an aquarium, commercially bred silver tetras suit beginners. They are active during the day and prefer a heavily planted tank with dim light, though plastic plants and driftwood work as long as hiding spots exist. Keep them in a school of 6–8 in a 30-gallon tank (100 cm or 39 inches long), with a pH of 6.0–7.5 and water temperature of 24–28 °C (75–82 °F). They are peaceful and can share a tank with other non-aggressive fish.
- Maximum length
- 8.0 cm (3+1⁄4 in)
- Temperature range (wild)
- 23–27 °C (73–81 °F)
- Temperature range (aquarium)
- 24–28 °C (75–82 °F)
- Ph range (aquarium)
- 6.0–7.5
- Minimum tank size
- 30 gallons (100 cm / 39 in long)
- Minimum school size
- 6–8 individuals
- Distribution
- Orinoco River basin and coastal river basins of Guyana, Suriname, French Guiana, Brazil, and Venezuela
Lore & Background
The silver tetra occurs in shallow, slow-moving streams with heavy vegetation in the Orinoco River basin and coastal river basins of Guyana, Suriname, French Guiana, Brazil, and Venezuela. In the wild, water temperatures range from 23–27 °C (73–81 °F). The fish can grow to a maximum length of 8.0 cm (3+1⁄4 in).
Its body is silvery-gray and round and flattened, with a slight olive green cast in some individuals. There is black at the base of the caudal fin, and some fish have a small dark spot near the gill covers. Males display a glow of red in the rear portion of the anal fin. The dorsal fin is fairly short, and the mouth is small with enlarged lips.
In the aquarium, commercially bred silver tetras are good for beginners. They are very active during daylight hours and prefer a heavily planted aquarium with dim light, though plastic plants with driftwood also suffice as long as hiding places are provided. They must be kept in a school of 6–8 individuals in a 30-gallon tank (100 cm long) with a pH of 6.0–7.5 and water temperature of 24–28 °C (75–82 °F). They are peaceful and can be kept with other non-aggressive fish.
Reader's Guide
The silver tetra is a staple in the freshwater aquarium hobby, valued for its peaceful nature and ease of care. The source article emphasizes that commercially bred specimens are suitable for beginners, requiring only a school of 6–8 fish in a 30-gallon tank with a pH range of 6.0–7.5 and temperatures of 24–28 °C (75–82 °F). Its preference for heavily planted aquariums with dim light makes it a classic choice for planted community tanks, though plastic plants and driftwood also work if hiding spots are provided. The fish is active during daylight hours and should be housed only with other non-aggressive species. Its natural distribution across northern South America—from the Orinoco basin to coastal rivers of Guyana, Suriname, French Guiana, Brazil, and Venezuela—highlights its adaptability to shallow, slow-moving, heavily vegetated streams. The species' maximum size of 8.0 cm and its silvery, round body with subtle red in the male's anal fin contribute to its enduring popularity as a peaceful, schooling characin.
Frequently Asked Questions
What is Ctenobrycon spilurus?
Ctenobrycon spilurus, commonly called the silver dollar tetra, is a small freshwater characin in the family Acestrorhamphidae. It has a round, laterally compressed body that is silvery-gray with an occasional faint olive-green cast, and a distinctive black spot at the base of the tail fin.
What is the minimum tank size for silver dollar tetras?
You should provide at least a 30-gallon (100 cm / 39 in) tank to keep a group of silver dollar tetras comfortably. This gives the fish enough open swimming space alongside the planted, slow-flowing environment they prefer in the wild.
How many silver dollar tetras should I keep together?
Aim for a school of at least 6 to 8 individuals, as they are shoaling fish that feel more secure and display natural behavior in groups. Keeping them in smaller numbers can lead to stress and excessive hiding.
What water parameters do silver dollar tetras need?
In the aquarium they do best at 24–28 °C (75–82 °F) and a pH between 6.0 and 7.5. These conditions roughly mirror the warm, slightly acidic-to-neutral waters of their native South American streams.
Where are silver dollar tetras native to?
They originate from the Orinoco River basin and the coastal river systems of Guyana, Suriname, French Guiana, Brazil, and Venezuela. In the wild they favor shallow, slow-moving streams with dense vegetation, where temperatures sit around 23–27 °C (73–81 °F).
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