Yellow Neon Tetra (Paracheirodon innesi) — Size Options: 1.5–3 cm

A yellow colour line of the Neon Tetra

The Yellow Neon Tetra is a yellow aquarium colour line of the Neon Tetra, Paracheirodon innesi, a small shoaling tetra from blackwater and clearwater tributaries of the Solimões River in South America. “Yellow” names the colour line rather than a separate species or subspecies, so every care decision here follows the biology of P. innesi. Adults stay tiny: Seriously Fish gives an adult length of 30 mm standard length, about 3 cm measured without the tail fin.

It suits a keeper with a mature, stable community aquarium at least 60 cm long who is happy to buy a proper group rather than one or two fish. Seriously Fish describes the species as generally peaceful, and a settled shoal moving between plants and open water is the reason to keep it. It is the wrong choice for a brand-new tank, for water that swings in temperature or chemistry, or for a community that includes any fish big enough to swallow it.

FishBase places the Neon Tetra in the family Acestrorhamphidae, the American tetras, and lists it as Least Concern on the IUCN Red List. Eschmeyer’s Catalog of Fishes puts it in the subfamily Megalamphodinae and records it from the Solimões River drainage of Brazil, Colombia and Peru. Older aquarium books and websites may still place it in Characidae; the fish is the same, only its family placement has moved.

Seriously Fish notes that the species has been selectively bred into several ornamental strains, including albino, golden, long-finned and diamond forms. A colour line such as this one shares the care needs of the species; what changes is the look.

Key numbers for planning

• Adult length: about 3 cm, recorded as 30 mm standard length.
• Aquarium: at least 60 cm long, with a mature filter.
• Group: at least 8–10 fish.
• Water: 21–25°C, pH 5.0–7.0 and 1–12 dGH, held steady.
• Diet: small complete foods with live or frozen variety.

Expect a small, active fish that spends its time in open midwater and looks its best as a group among plants and wood. Seriously Fish recommends adding other schooling species for extra security, which turns a single shoal into a calmer, more natural display.

What one purchase supplies

Each purchase supplies one live Yellow Neon Tetra in the size you pick: 1.5–2 cm, 2–2.5 cm or 2.5–3 cm. Build the shoal by raising the quantity to match your plan, so a group of ten means a quantity of ten. The live size selector shows which sizes can be ordered when you check out.

The size you select is the size supplied, not the adult size. Plan space and companions around the 3 cm adult described above, and choose the dispatch size with your existing community in mind: a smaller fish is an easier mouthful for a larger companion. For a new tank set up around a fresh group, any of the three sizes follows the same care plan.

Sex is guaranteed only when the selected option explicitly states male or female. This Yellow Neon Tetra listing has no sex-guaranteed option. Fish are chosen by the size you select, not by sex.

Gallery images have been digitally enhanced to improve image quality. Natural colour, pattern, size and maturity can vary between live animals. Apparent colour also shifts with lighting, viewing angle and the fish’s surroundings, so individuals in one order may not match each other exactly, and a vivid photograph says nothing about health on its own.

Planning an order

A keeper with a mature 60 × 30 cm aquarium and no other fish might order ten fish in one size, so the whole group arrives together and settles on the same routine. A keeper adding tetras to an established community would first confirm that no resident could swallow even the smallest 1.5–2 cm fish, then order enough to make a proper group rather than topping up with two or three.

If you are still choosing between species, our tetras collection brings the other small shoaling tetras together in one place for comparison.

Understand its size, wild home and lifespan

Adult size

Plan the aquarium around a 3 cm adult. Seriously Fish records 30 mm standard length for the species, while FishBase records a maximum of 2.5 cm standard length for males and unsexed fish. Standard length runs from the snout to the base of the tail and leaves out the tail fin. Working from the larger figure keeps tank, filter and companion decisions on the safe side.

Where it lives in the wild

FishBase describes the Neon Tetra as a pelagic freshwater fish of blackwater or clearwater stream tributaries of the Solimões River. Pelagic fish live in open water rather than on the bottom, which is why a group uses the middle of the aquarium and needs uninterrupted swimming space there. Wild adults feed on worms, small insects, crustaceans and plant matter, a mixed diet that shapes the feeding plan below.

Seriously Fish’s aquarium suggestions of driftwood, dried leaf litter, alder cones and fairly dim lighting echo that stream habitat. They are layout choices rather than requirements: the Tropical Fish Co care guide treats dark substrate, tannin-stained water and any one aquascape style as design decisions, not welfare thresholds.

Lifespan and commitment

OATA’s care sheet for tetras and pencilfish notes that, although small, these fish can live several years in a well-matured set-up with good water quality. Treat a group as a commitment of several years. Age and condition at purchase, water stability, diet and exposure to disease all influence how long individual fish live, so steady husbandry is the most useful thing you can control.

Choose an aquarium at least 60 cm long

Start with length. FishBase compiles a minimum aquarium size of 60 cm for Paracheirodon innesi, and Seriously Fish recommends a base of at least 60 × 30 cm, which it puts at about 54 litres. A long, lightly stocked tank gives a small midwater shoal room to move as a group; a short, crowded tank with the same nominal litres does not.

Litres on a box are a poor guide by themselves. Two tanks sold as 40 litres can differ in length and footprint, and substrate, rocks and wood reduce the water actually available to the fish. OATA’s general tetra guidance suggests at least 45 litres for a small shoal of a smaller species and notes that larger aquariums keep temperature and water quality more stable, which is another reason to size up where you can.

A five-step check before buying

1. Measure the internal length of the aquarium and start at 60 cm or more.
2. Work out the usable water once substrate and décor are in.
3. Confirm the filter is biologically mature and that ammonia and nitrite test at zero.
4. Allow room for a group of at least 8–10 Yellow Neon Tetras.
5. Add every adult tank mate to the plan, not only the fish you are buying now.

Filtration and heating for a 60 cm tank

Seriously Fish’s worked example for a tank of about 54 litres suggests a filter turning the water over four to five times an hour, which means a unit rated at roughly 215–270 litres per hour, and a heater of around 50 W to hold 21–25°C in a room of about 20°C. OATA adds that smaller tetras want a gentle current, so position the outlet to leave calm water somewhere in the tank.

A thermostatic heater with a separate thermometer is the dependable choice in many UK homes, where seasonal and overnight drops in room temperature would otherwise reach the aquarium. Measure the water itself rather than the room, and size the heater from the maker’s instructions for your tank volume and room.

If the aquarium is still new, our guide to setting up a first tropical tank walks through maturing the filter before any fish arrive. The RSPCA recommends fishless cycling for new set-ups, and OATA warns that stocking too quickly leads to “new tank syndrome”, when there are not enough nitrifying bacteria to cope with the extra waste and ammonia and nitrite rise to harmful levels.

Keep the water soft, stable and at 21–25°C

Keep Yellow Neon Tetras at 21–25°C and pH 5.0–7.0 in soft to moderately soft water of 1–12 dGH, and keep those values steady. The temperature and pH targets sit inside both species profiles below; the hardness figure is Seriously Fish’s aquarium range.

The two species profiles agree on 21–25°C and pH 5.0–7.0, so that is the band to aim for. Seriously Fish’s range reaches down to pH 4.0, a very acidic figure better left to deliberate blackwater set-ups than used as an everyday target, and up to pH 7.5, so steady water a little above neutral still falls within its species range. OATA’s figures are general guidance for captive-bred tetras as a group and are not species-specific; their warmer and more alkaline end goes beyond both species profiles, so use them only where they agree with the band above.

Water quality comes first

Whatever the chemistry, OATA’s sheet sets ammonia and nitrite at zero and nitrate at no more than 20 mg per litre above your normal tap water level. A fish kept in perfect pH but rising ammonia is in more danger than one kept at a slightly different pH in clean, stable water.

Working with UK tap water

UK hardness varies with local geology and supply, and your water company can tell you its local figures. Those figures are a starting point rather than the result in your aquarium, so test the tank itself. A domestic ion-exchange softener does not automatically make water suitable for soft-water fish. Our guide to aquarium water chemistry explains which values to test and why, and the water parameter matcher compares your measured results with the range above.

Matching the water they come from

Before ordering, ask us about the water the fish are held in, then avoid forcing them quickly from one set of values to another. A gradual adjustment inside the target band protects a small fish far better than a rapid change towards an ideal number.

Furnish a planted layout with open midwater space

Give the group a clear midwater lane with cover around it. Seriously Fish suggests a sandy substrate with driftwood roots and branches, plus dried leaf litter to emphasise the natural feel. As the leaves break down they support microbe colonies that fry can feed on, and alder cones are useful in the same way. There is no need for natural peat, which Seriously Fish describes as unsustainable and environmentally destructive to collect.

The species seems to do best under fairly dim lighting, according to Seriously Fish, which suggests plants that cope with those conditions, such as Microsorum, Taxiphyllum and Cryptocoryne. OATA’s general sheet asks for gravel or sand, live plants for cover (or plastic plants and aquarium ornaments where live plants are not used), space to swim and a gentle current for smaller species.

A layout checklist

• Open water along the front and centre so the shoal can cruise as a group.
• Plants and wood at the back and sides to give the fish somewhere to retreat.
• Subdued areas beneath taller plants or wood where the fish feel less exposed.
• A filter outlet placed so that part of the tank stays calm.
• Enough light for the plants you choose, run on a regular daily light and dark cycle.

Dark substrate, tea-coloured water and one particular aquascape style are design choices rather than welfare requirements. Choose what you enjoy looking at, as long as the fish still have open water, cover and stable conditions. An open lane also makes feeding and daily observation easier, which pays off when you are checking that every fish is eating.

Feed small, varied meals the shoal clears in minutes

Feed once a day, offering only what the group eats within a few minutes, as OATA’s tetra and pencilfish sheet recommends. Use a good-quality flake, granule or micro-pellet as the staple, crushed small enough for the smallest fish in the group to swallow.

In the wild, FishBase records adults eating worms, small insects, crustaceans and plant matter. Seriously Fish describes the species as likely omnivorous and says that, although it may survive on dried foods, it does best with a varied menu that includes live and frozen bloodworm, mosquito larvae, Daphnia and Moina.

Building the menu

• Staple: a small complete flake, granule or micro-pellet.
• Variety: small frozen or live foods such as Daphnia, Moina, mosquito larvae and small bloodworm.
• Convenience: freeze-dried Daphnia or bloodworm, which Seriously Fish also lists, when live and frozen foods are not to hand.

One treat food never replaces the complete staple. Watch each feed to see that the shyest fish actually reach the food, and remove any regular excess rather than leaving it for snails or bottom-dwelling fish to clear. OATA warns that uneaten food breaks down and releases toxic waste into the water, which quickly undoes good water quality in a small tank.

Feeding the smallest fish

Fish from the 1.5–2 cm grade have small mouths, so crush flake finely or choose the smallest micro-pellet, and pick frozen foods such as Daphnia or Moina over larger bloodworm until the fish grow. Particle size should fit the fish rather than follow a fixed rule.

Feeding in a mixed community

When faster or larger species share the tank, check at every meal that the tetras get their share. Feeding speed is one of the traits to compare when you choose companions, and a change in body condition is one of the early signs OATA lists as worth watching. If a tetra keeps missing out, rethink the stocking rather than simply adding more food, which only loads the filter.

Keep a steady routine and act early on health changes

Weekly maintenance

• Change 25% of the water at least once every week, siphoning solid waste from the substrate, as OATA’s care sheet strongly recommends.
• Test the water at least once a week so that ammonia and nitrite never build up.
• Treat replacement water with a tap water conditioner to remove chlorine or chloramine.
• Check the filter for blockages. If it needs cleaning, do not run it under the tap; rinse the media lightly in tank water removed during the water change so that fewer beneficial bacteria are lost.

The RSPCA explains why the filter matters so much: fish release ammonia, which is toxic, and a working biological filter lets beneficial bacteria convert it to nitrite, also toxic, and then to the safer nitrate. OATA stresses that good husbandry is essential because tetras can be stressed by even the smallest amounts of ammonia, so a steady routine matters more than any single deep clean.

Choosing and watching stock

Seriously Fish warns that years of commercial breeding have affected the genetic vigour of the ornamental Neon Tetra, so deformities and ill health are widespread and stock needs careful selection. It also notes that the species is susceptible to the ailment known as “neon tetra disease”, named because it was first diagnosed in Neons, although it can affect many other species. For an online order, the equivalent of watching fish in a shop is close observation during the first weeks at home.

OATA lists the changes worth noticing early:

• Swimming: hanging at the surface, sitting on the bottom or erratic movement.
• Colour: turning darker or paler than normal.
• Temperament: hiding more than usual or a change in aggression.
• Breathing: gill covers moving faster or slower than normal.
• Appearance: white spots, fluffy growths, or lost fins or scales.
• Condition and feeding: a change in body weight or lost interest in food.

None of these signs identifies a disease on its own. Test temperature, ammonia and nitrite first, compare the affected fish with the rest of the group, and separate an unwell fish when that is practical. The RSPCA’s pet fish health advice and the MSD Veterinary Manual both put water quality at the centre of any investigation, and OATA’s find a fish vet directory helps UK keepers reach a vet who treats fish. Avoid blanket salt, heat or medicine treatments chosen from a symptom list, and contact us if changes persist once the water tests clean.

Receive, film and settle the fish on arrival day

Have the aquarium ready before you order: filter mature, ammonia and nitrite at zero, heater and thermometer running steadily. Every order is hand-bagged in pure oxygen and packed in an insulated poly box, with a heat pack when the weather calls for it, then carried by a tracked, licensed live-animal courier. The tracking number and your confirmed delivery date arrive by email so that you know when to be in.

On the day

1. Be at the delivery address to receive the parcel, because live fish cannot be left unattended.
2. Start a short, continuous unboxing video while the parcel is still sealed, with the outer box in view.
3. Keep filming as you open the parcel in one take, showing the fish still inside the sealed bag before anything is disturbed. The parcel should be opened and inspected the same day it arrives.
4. Acclimatise the fish slowly: float the bag for 20–30 minutes before releasing them.
5. Release the fish without pouring the bag water into your tank.
6. If anything has gone wrong, contact us the same day with your order number and the video; WhatsApp is fastest, and we will arrange a replacement or refund.

The delivery and Live Arrival Guarantee page sets out the full terms, including the need for a continuous unboxing video with any claim.

The first two weeks

Keep disturbance low after release and watch how the group settles. A shoal may spread out once it relaxes and draw closer together after a disturbance, which is normal behaviour rather than a problem. Test ammonia and nitrite over the following days rather than assuming clear water is safe, especially when a group of ten or more has just joined an existing community.

If the new fish are joining established stock, the MSD Veterinary Manual’s emphasis on biosecure separation of incoming fish is a good reason to hold them first in a separate, mature quarantine tank. That tank needs the same care as the display: a matured filter, a heater and the same 21–25°C band.

Breeding needs a separate, very soft tank

Neon Tetras scatter their eggs, and FishBase notes that in aquaria the female lays a relatively small number, which hatch in about 24 hours. Seriously Fish advises setting up a dedicated tank if you want to raise decent numbers of fry.

The Seriously Fish breeding set-up

• Very dim lighting, with clumps of fine-leaved plants such as java moss or spawning mops for the eggs, or a mesh over the base with holes large enough for eggs to fall through but too small for the adults to reach them.
• Soft, acidic water of pH 5.5–6.5 and gH 1–5, at around 26.5–29°C.
• A small air-powered sponge filter bubbling away gently.
• A group of about half a dozen fish of each sex, conditioned with plenty of small live foods.
• Removal of the adults once eggs have been laid.

That 26.5–29°C breeding temperature is warmer than the 21–25°C routine range and belongs only in the spawning tank, never in the display aquarium. The breeding pH and hardness sit at the soft, acidic end of the routine range.

Seriously Fish notes that sexually mature females are normally noticeably rounder-bodied and a little larger than males, which helps when choosing breeding fish from an established adult group. OATA adds that most fish are difficult to sex unless they are breeding, so young fish at dispatch size are hard to separate by eye.

Choose small, calm companions that share soft water

Choose companions that cannot swallow a 3 cm fish, share the 21–25°C soft-water band and move at a similar pace. OATA advises that small tetras such as Neons should not be kept with any fish large enough to eat them, and that tetras mix best with species of a similar size and temperament.

Seriously Fish suggests the species is best kept alongside similarly sized characids, hatchetfish (gasteropelecids), pencilfish (lebiasinids), smaller callichthyid or loricariid catfish and non-predatory, small-to-medium-sized cichlids. It also recommends including other schooling fish, which gives the tetras extra security and a more natural-looking display.

Screen every candidate

• Adult body and mouth size compared with a 3 cm tetra.
• A shared range within 21–25°C, pH 5.0–7.0 and soft to moderately soft water.
• Activity level and feeding speed.
• Swimming zone and each species’ own group size.
• Any tendency to nip fins or defend territory.
• The real footprint and usable volume of your tank.

Similar size is only the first screen. Peaceful Corydoradinae, Harlequin Rasboras or Ember Tetras can be candidates once they pass those checks, and each needs its own group and space counted into the stocking plan.

Take a small, non-predatory cichlid as a worked example. Check that its adult mouth could not take a 3 cm fish, that its own water range reaches into 21–25°C and pH 5.0–7.0, and that the tank still has room for any territory it defends once the tetra group has its open water. If any answer is no, leave it out.

Shrimp and bettas

FishBase records small crustaceans in the wild adult diet, so treat very small shrimp, shrimplets, fry and other bite-sized animals as possible prey. That is a precaution rather than a prediction that every fish will hunt every shrimp. A Betta is not a reliable match either: individual behaviour, space and escape routes decide the outcome, so try one only with a backup plan to separate them if chasing starts.

Mixing with other Neons and with Cardinal Tetras

A Yellow Neon Tetra is the same species as the standard Neon Tetra, so its water, space and diet needs are identical; only the colour line differs. If you plan to keep both, count every fish in the stocking plan and give the aquarium the length and filtration that the whole group needs.

The Cardinal Tetra, Paracheirodon axelrodi, is a different species in the same genus. FishBase compiles 23–29°C for it and a maximum of 3 cm standard length. Where the two share a tank, the practical temperature band narrows to 23–25°C, the part of the Cardinal’s range that also sits inside the 21–25°C routine range for Neons. Keep each species as its own proper group rather than treating a few of each as one shoal.

Check the name, not the colour

Fish sold with “neon” in the name are not all Paracheirodon innesi, and colour alone can mislead, so confirm the scientific name before assuming the same care. For the species in more depth, including how Neons and Cardinals compare, read our complete Neon Tetra care guide.

Common questions before you buy

How big does a Yellow Neon Tetra get?

Plan for an adult of about 3 cm. Seriously Fish records the species at 30 mm standard length, measured without the tail fin, and FishBase records a maximum of 2.5 cm standard length. Any companion big enough to swallow a fish of that length is unsuitable, so plan tank mates around the adult, not the fish on arrival.

What size tank does a Yellow Neon Tetra need?

Use an aquarium at least 60 cm long, the minimum aquarium size FishBase compiles for the species. Seriously Fish suggests a base of at least 60 × 30 cm, about 54 litres. Judge a tank by its length, usable water and mature filtration rather than the litre label alone, and leave room for every adult tank mate.

How many Yellow Neon Tetras should be kept together?

Keep a group of at least 8–10, as Seriously Fish advises. FishBase and OATA give five as the minimum, and OATA notes that tetras kept singly or in too small groups will often become stressed. A bigger group needs a correspondingly longer aquarium and a filter matured for the extra load.

Are Yellow Neon Tetras good for beginners?

They can suit a careful beginner with a fully matured aquarium, and the Tropical Fish Co Neon Tetra care guide rates the species intermediate. The filter must be biologically mature, ammonia and nitrite must test at zero and the water must stay stable before the group arrives, so a newly set-up tank is the wrong place to start.

What does this tetra eat?

Feed a small complete flake, granule or micro-pellet as the staple, once a day and only what the group eats within a few minutes, as OATA's tetra care sheet advises. Add variety with small live or frozen foods such as Daphnia, Moina and bloodworm; Seriously Fish notes the species does best on a varied menu rather than dried food alone.

What temperature and pH does this tetra need?

Keep it at 21–25°C and pH 5.0–7.0, where the FishBase and Seriously Fish species ranges agree, in soft to moderately soft water of 1–12 dGH. Stability matters more than any single number, so match the water the fish have been held in gradually and avoid sudden changes.

Is this tetra aggressive, and does it nip fins?

Seriously Fish describes the Neon Tetra as generally peaceful, which makes it a good resident for a well-planned community aquarium. The bigger risk runs the other way: OATA advises that small tetras such as Neons should not be kept with any fish large enough to eat them.

Which fish can live with this tetra?

Seriously Fish suggests similarly sized characids, hatchetfish, pencilfish, smaller callichthyid or loricariid catfish and non-predatory, small-to-medium-sized cichlids. Screen each candidate for adult size, water range, activity and feeding speed, and treat very small shrimp, shrimplets and fry as possible prey.

How does a Yellow Neon Tetra arrive alive in the UK?

Film a short, continuous unboxing video from the sealed parcel onward, because the Live Arrival Guarantee needs one for any claim. The fish travel hand-bagged in pure oxygen inside an insulated poly box, with a heat pack when the weather calls for it, carried by a tracked, licensed live-animal courier. Someone must be at the address to receive the parcel; open and inspect it the same day, float the bag for 20–30 minutes before releasing the fish, and never pour the bag water into the tank.

Sources and further reading

These public sources support the identity, care and health guidance on this page.

• FishBase: Paracheirodon innesi: identity, family, recorded size, compiled water values and wild diet.
• Seriously Fish: Paracheirodon innesi: aquarium size, water, diet, behaviour, sexing and breeding.
• Eschmeyer’s Catalog of Fishes: Paracheirodon innesi: accepted name, family, subfamily and distribution.
• FishBase: Paracheirodon axelrodi: Cardinal Tetra comparison.
• OATA: How to look after tetras and pencilfish: general tetra water, maintenance, feeding and compatibility guidance.
• RSPCA: choosing an aquarium for pet fish: filtration and water quality.
• RSPCA: pet fish health: warning signs and when to seek help.
• MSD Veterinary Manual: management of aquarium fish: water quality and separating incoming fish.
• OATA: find a fish vet: UK veterinary directory.