Lemon tetra

Quick facts

Adult size

5 cm

Lifespan

can live up to 8 years; captive average is 4-6

Tank zone

mid

Temperament

peaceful

Difficulty

beginner

Schooling

recommended 6+ (critical minimum 4, thrives at 8+)

Water parameters

Temperature

23–28°C

pH

5.5 to 7.5

Hardness

1 to 15 dGH

Tank requirements

Minimum volume

90 L

Minimum length

75 cm

Flow

low

Lighting

moderate

Substrate

any

Driftwood

preferred

Hiding spots

needed

Feeding

Diet: omnivore, feeds primarily at the mid.

Undemanding. Flake food, micro pellets, frozen bloodworm, frozen brine shrimp, frozen daphnia. Feeds in the midwater column. Not competitive at feeding time; won't outcompete anyone but also doesn't get pushed around. Twice-daily feeding in moderate amounts. Color improves with a varied diet. Live baby brine shrimp is a treat that brings out feeding behavior.

Compatibility

• Peaceful schooling tetra that fits into any community with non-aggressive species. No nipping, no territorial behavior, no drama.
• Schools best in groups of 8+ where the yellow coloration intensifies through competition between males. Small groups look washed out.
• Good companion for planted tanks, community tanks with dwarf cichlids, and any setup with similarly sized peaceful fish.
• The lemon-yellow body color with a red upper eye is subtle compared to neons or cardinals but in a big group against a dark background it's surprisingly attractive.

Habitat

Native to the Tapajos River basin in central Brazil. Found in slow-moving, clear to slightly tannin-stained water with sandy substrates and submerged vegetation. The species has been in the aquarium hobby since the 1930s. The common name overpromises slightly: the fish isn't bright lemon-yellow like a tang or a lab cichlid. It's a translucent pale yellow with a hint of green, a prominent red and black upper iris, and black leading edges on the anal and dorsal fins. The color only looks impressive in a large group (10+) under warm-toned lighting against a dark background. Under cool white LEDs on pale gravel, they look like plain glass tetras. This color dependency is the main reason lemon tetras are overlooked in stores, where display tanks rarely show them at their best. Males develop more intense yellow and a broader black edge on the anal fin; females are paler and rounder. All stock is tank-bred. Size is about 5 cm at maturity.

Breeding

Egg scatterer, moderate difficulty. Condition pairs with frozen food for a week. Breeding tank with soft acidic water (pH 5.5-6.5, GH below 6), dim lighting, fine-leaved plants or spawning mops. Temperature at 26–27°C. Spawning occurs at dawn. The pair scatters 200-300 eggs among the plants. Eggs are light-sensitive; keep the tank dark. Remove adults after spawning. Eggs hatch in about 24 hours. Fry are tiny and need infusoria for the first 4-5 days, then baby brine shrimp. Growth is moderate. The species is less commonly bred by hobbyists than other tetras, mostly because the commercial supply is cheap and abundant.

Common problems

Color washed out in poor conditions is the main complaint. The fix is environmental: dark substrate, warm lighting (3000-4000K), tannin-stained water, and a large group. Once those conditions are met, lemon tetras go from forgettable to one of the prettier community tetras available. Health-wise, they're hardy. Ich can appear in stressed new purchases. Fin rot is rare except in degraded water. The species is one of the longer-lived small tetras; 6-8 years is common in well-maintained tanks. Old fish fade in color gradually.

Bioload

Bioload coefficient: 1.4 (5 cm body, slightly heavier-built than rummynose with mellower activity; rounded down from formula).

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

• How to cycle a fish tank
• Stocking ideas by tank size