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Neon Tetra

Fish

The tiny electric-blue schooler that turns any planted tank into a shimmering river scene!

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🤓 Did you know? A neon tetra's iridescent blue stripe isn't pigment - it's produced by light-reflecting cells called iridophores. That stripe actually dims or goes nearly dark while the fish sleeps at night, a completely natural nocturnal color change rather than a sign of illness.

🗓️ The first week

The numbers a new owner needs in the first week, each from the article it links to. Rows with no link come from the encyclopedia.

How many: Ten. Groups of ten showed less aggression and darting and fed sooner than smaller groups. Six is the floor, and one species of ten beats two species of five.Enrichment guide →
Tank size: 10 gallons for a school of 6, a 20-gallon long for the better 10 to 15. Schooling plays out horizontally, so long beats tall.Setup guide →
Temperature: 72 to 78°F as the target inside a workable 70 to 81°F, held steady: swings stress them more than a slightly imperfect setting. A heater on any tank of 10 gallons or more.Setup guide →
Water chemistry: Soft and slightly acidic, pH 6.0 to 7.0 with low hardness, which is a different water from what a guppy tolerates. Test your source water first. Ammonia and nitrite read zero.Setup guide →
Filtration and substrate: Gentle flow, a sponge filter or a baffled hang-on-back, over fine gravel or sand. A darker substrate makes the neon stripe pop.Setup guide →
Light and blackwater: Dim to moderate for 8 to 10 hours a day. Driftwood and Indian almond leaves for tannins, dense plants and floating cover; bright light stresses a fish from shaded streams.Setup guide →
Feeding schedule: Twice daily, what the school finishes in about 2 to 3 minutes. Fry and juveniles 3 to 4 small feeds a day, adults from about 6 months on twice.Feeding guide →
Diet: A quality tropical flake crushed fine, or a micro-pellet, for a mouth only 1 to 2mm across. Baby brine shrimp, daphnia or chopped bloodworms 2 to 3 feeds a week. Food too large is spat out, which starves the fish while the tank looks fed.Feeding guide →
A dead fish: Never leave one in the tank or let the others scavenge it. Neon tetra disease has no cure, and fish that eat an infected body contract it.Feeding guide →
Quarantine: 2 to 4 weeks in a separate tank before a new fish joins the school, given the disease risk this species carries.Setup guide →
Tankmates: Peaceful, similarly sized community fish. Nothing with a mouth big enough for a neon, and no fin nippers.Handling guide →
Water changes: 25 to 30% weekly from the substrate, with conditioned water at tank temperature. Test nitrate first: under 20 ppm the routine is right, past 40 ppm the next change is 50%.Aquarium Water Changes →
Budget: $1 to $3 a fish, occasionally $5, a school of 6 to 12 for $10 to $40. Setup roughly $100 to $300. Vet care does not apply; water quality and over-the-counter treatment are the whole of it.Cost guide →
Lifespan: Around 5 years with stable care; average conditions see closer to 2 to 3.Cost guide →
Adult size: 1 to 1.5 inches (2.5 to 4 cm).
Water chemistry, the wider picture: KH holds pH in place, and dosing pH-up or pH-down against it is how keepers crash a tank. Work with what the source water gives you.Freshwater pH, GH, and KH →
Cycle first: Cycle the tank fully before any neon goes in. A fish this small has no margin for an ammonia spike, and the treatable conditions on the health list all trace to water.Enrichment guide →
Power outage: Oxygen is the threat, not darkness. Unplug the filter rather than letting it sit dead in the water, and keep the surface moving.Power outage guide →

🚨 Emergency card

Test the water first, then act on these today. Aquatic vets are rare, so nearly all of this is handled at home.

Small white spots like grains of salt, flashing against decor, rapid breathing: ich, treatable
Ragged or bloody-edged fins: fin rot, treatable
Restless swimming at night, fading color along the back, lumps under the skin, a curved spine: neon tetra disease, no cure, and the fish is separated so the others cannot eat it

Everything treatable here traces back to water quality and stability. Neon tetra disease is likely over-diagnosed; true cases are uncommon in a well-established tank.

From Common Neon Tetra Health Issues (Including the Disease Named After This Fish) →

📰 Where to go next

How Much Does Neon Tetra Ownership Really Cost?

$1 to $3 a fish, why the purchase is a group, and the $100 to $300 that goes into the tank around them.

Neon Tetra Tank Setup: Soft Water, Dim Light, and a Blackwater Feel

10 gallons for six and a 20 long for ten, soft acidic water, gentle flow, dim light, and the blackwater detail.

Neon Tetra Feeding: Schedule, Diet, and the Rule That Prevents an Outbreak

Twice a day in 2 to 3 minutes, why a 1 to 2mm mouth changes what you buy, and the rule that stops an outbreak.

Neon Tetras Aren't Handled, But the School Size Genuinely Isn't Optional

Why this is a netting-only fish, the school floor, and the tankmates that turn a shoal into lunch.

Common Neon Tetra Health Issues (Including the Disease Named After This Fish)

Neon tetra disease and why it is over-diagnosed, plus ich, fin rot, and swim bladder trouble.

Neon Tetra Enrichment: Someone Counted, and the Number Is Ten

The 2010 study that tested group size properly, and why the answer came back ten rather than six.

🛒 What to buy

10-gallon tank for a school of six, or a 20-gallon long for ten to fifteen

Ten neon tetras rather than six, where the tank supports it

Aquarium heater

Sponge filter, or a hang-on-back unit you can baffle

Fine gravel or sand in a darker color

Driftwood and Indian almond leaves

Dense midground live plants and floating plants

Dim to moderate aquarium light on a timer

Liquid water test kit

Water conditioner

Micro or nano pellet, or a tropical flake to crush

Frozen baby brine shrimp, daphnia, or bloodworms

Prices and the reasoning behind each item are in How Much Does Neon Tetra Ownership Really Cost?.

❓ Frequently Asked Questions

What size tank does a school of neon tetras need?

10 gallons for a school of 6, which is the practical floor. For the better group of 10 to 15, move up to a 20-gallon long. Schooling happens sideways, so favor length over height.

How often should I feed neon tetras?

Twice a day for adults, morning and evening, only as much as they finish in about 2 to 3 minutes. Fry and juveniles need 3 to 4 small feedings a day until about 6 months old.

So is six enough?

Six is the number most care sheets give and the study found ten better. The smallest functioning shoaling unit is often put at six to eight, so six is a floor rather than a target. If you can house ten, house ten.

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Neon Tetra

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