Ember tetra

Quick facts

Adult size

2 cm

Lifespan

can live up to 4 years; captive average is 2-3

Tank zone

mid

Temperament

peaceful

Difficulty

beginner

Schooling

recommended 6+ (critical minimum 4, thrives at 10+)

Water parameters

Temperature

23–29°C

pH

5.5 to 7.0

Hardness

1 to 10 dGH

Tank requirements

Minimum volume

40 L

Minimum length

45 cm

Flow

low

Lighting

moderate

Substrate

any

Hiding spots

needed

Feeding

Diet: omnivore, feeds primarily at the mid.

Tiny mouth limits food size. Crushed flake, micro pellets (0.5–0.8 mm), frozen cyclops, and baby brine shrimp. Standard-sized flake needs to be ground between fingers before feeding. They pick at food in the water column and rarely take anything from the surface film or the bottom. Two small feedings per day. Color improves noticeably on a diet that includes carotenoid-rich foods (spirulina, daphnia).

Compatibility

• Peaceful with everything but too small to house with any fish that could eat them. Even a hungry honey gourami might take a shot at a 2 cm tetra.
• Best kept with other nano species: pygmy corys, chili rasboras, celestial pearl danios, small shrimp. Basically anything under 4 cm.
• Safe with all dwarf shrimp. Too small to eat even baby cherry shrimp.
• Not a good tankmate for active or boisterous fish (danios, barbs) that will outcompete them for food and stress them with constant movement.

Habitat

Native to the Araguaia River basin in central Brazil. Discovered relatively recently (described in 1987) compared to most aquarium staples. The body is a warm orange-red that varies in intensity with water conditions, diet, and mood. Reaches only 2 cm, making it one of the smallest tetras commonly kept. The small size means they're perfect for nano tanks (30 L) and planted aquascapes where larger fish would look out of place. They occupy the midwater column, hovering among plants and drifting slowly rather than darting like many tetras. Groups of 10+ show the best natural behavior and coloring.

Breeding

Egg scatterer. Breeds readily in a well-planted tank with soft acidic water. The fish scatter adhesive eggs among fine-leaved plants (java moss, subwassertang). Parents will eat eggs they find, but in a densely planted tank some survive. Fry are microscopic and need infusoria or commercial liquid fry food for the first week, then crushed dry food and baby brine shrimp. In a mature, densely planted nano tank with no predators, a small colony will slowly grow on its own without intervention.

Common problems

Sensitivity to water quality swings. Embers are not fragile once established, but they don't tolerate ammonia or nitrite at all, and large water changes that shift temperature or pH can cause stress. Acclimate slowly. Color fading is the most common complaint; it's almost always a sign of stress, poor diet, or washed-out lighting. Under warm white LEDs against a dark substrate, embers glow. Under cool white LEDs against a white substrate, they look pale. Neon tetra disease can affect them (it's not limited to neons despite the name). Lifespan is 2-4 years; deaths at under 1 year are abnormal.

Bioload

Bioload coefficient: 0.4 (tiny species; size formula compresses too low so floor-lifted to ~40% of a neon).

Bioload coefficients are calibrated against the neon tetra as the anchor (1.0). See the methodology page for the formula and how each value was derived.

Further reading

• Stocking ideas by tank size