Black neon tetra

Quick facts

Adult size

3.5 cm

Lifespan

can live up to 6 years; captive average is 3-5

Tank zone

mid

Temperament

peaceful

Difficulty

beginner

Schooling

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

Water parameters

Temperature

23–27°C

pH

5.5 to 7.5

Hardness

2 to 15 dGH

Tank requirements

Minimum volume

75 L

Minimum length

60 cm

Flow

low

Lighting

moderate

Substrate

any

Hiding spots

needed

Feeding

Diet: omnivore, feeds primarily at the mid.

Easy to feed. Flake food, micro pellets, frozen daphnia, frozen brine shrimp, and frozen bloodworm are all accepted without fuss. Mouths are small for a tetra of this size, so crush large flake pieces or use a brand with smaller flakes. They feed in the midwater column and generally ignore food once it hits the bottom. Twice daily in small amounts works better than one large feeding. They'll eat just about anything offered, which makes them reliable in community tanks where multiple species need different food types. Condition breeding pairs with frozen food twice daily for a week before attempting to spawn.

Compatibility

• One of the hardiest small tetras available. Tolerates a much wider range of water chemistry than neon or cardinal tetras, including moderately hard water up to 15 dGH. A good pick for keepers on municipal tap water who don't run an RO system.
• Not susceptible to neon tetra disease (Pleistophora hyphessobryconis), despite the confusing common name. This is a different genus entirely (Hyphessobrycon, not Paracheirodon). Bacterial infections that mimic NTD symptoms can still occur but respond to treatment.
• Schools well with other peaceful tetras, rasboras, and small catfish. Groups of 10+ in a planted tank are the best way to see the black-and-gold stripe contrast at its most striking. In smaller groups they fade in color and school less tightly.
• Good dither fish for shy species. A bold, active black neon school in the midwater zone signals safety to bottom-dwellers and cichlids that tend to hide.

Habitat

Found in tributaries of the Paraguay River basin in the Mato Grosso region of Brazil. Wild habitat is slow-moving, heavily shaded streams stained brown with tannins from decomposing vegetation. The water is soft and acidic, but captive-bred stock (which is the vast majority of what's sold) handles a much broader range. The color pattern is a bold black horizontal stripe running from behind the eye to the base of the tail, topped by a thinner iridescent white-gold line. Under good lighting, the gold line fluoresces slightly. The overall effect is more understated than a neon tetra but in a big school against a dark background, the visual impact is excellent. They look best in tanks with dark substrate and subdued lighting, which mimics their natural blackwater habitat and brings out the contrast between the stripes. Commercially bred in large numbers across Southeast Asia and Eastern Europe. Inexpensive and almost always available.

Breeding

Egg scatterer, and more reliably bred in home aquariums than neon tetras. Condition a breeding pair with high-quality frozen food for 7-10 days. The breeding tank should be small (20–30 L), dimly lit, with a thin layer of fine-leaved plants or a spawning mop on the bottom. Water needs to be soft and acidic: pH 5.5-6.5, GH below 4. Temperature at the upper end of their range (26–27°C) helps trigger spawning. Males display more intensely colored stripes than females, and females are noticeably rounder when full of eggs. Spawning usually happens at first light. Eggs are scattered among the plants and are adhesive. Adults eat eggs, so remove them promptly after spawning. Eggs are light-sensitive; keep the tank covered or in a dim room. Hatching takes 22-26 hours at 25°C. Fry are tiny and need infusoria or liquid fry food for the first 3-4 days, then transition to baby brine shrimp nauplii. Growth is steady but not fast; juveniles reach sellable size in about 3 months.

Common problems

Remarkably hardy for a small tetra. Disease problems are uncommon in established tanks with stable water. The main issue isn't medical but behavioral: groups under 6 fish are timid, pale in color, and hide behind decor. This is true of most schooling tetras but black neons show it more obviously because the stripe contrast is so dependent on the fish being relaxed and confident. In groups of 10+, the behavior transforms completely. Ich can appear in newly purchased fish that were stressed during transport; treat with elevated temperature (30°C for 3 days) or a half-dose of malachite green. Some keepers report occasional swim bladder issues in older fish (3+ years), presenting as difficulty maintaining buoyancy. This is usually age-related and not treatable. Columnaris (cotton-wool disease) can hit if water quality lapses, showing as white fuzzy patches on the body or fins. Responds to antibiotics if caught early. The single most common "problem" is just keeping too few of them and then wondering why they look washed out.

Bioload

Bioload coefficient: 0.9 (smaller than neon (3.5 cm) but hardier and heavier feeder; nudged up from formula output of 0.74).

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