Neon Tetra Care Guide: Paracheirodon innesi for UK Aquarists

The neon tetra (Paracheirodon innesi) is one of the most popular freshwater fish in the UK hobby, and after keeping them for over 15 years I still think they are one of the best species you can put in a planted community tank. There is nothing quite like a proper school of 20 or more moving through a dark aquascape — the electric blue stripe catches the light in a way that photographs never fully capture.

This guide draws on data from FishBase^[1] and Seriously Fish^[2], cross-referenced with 15 years of keeping this species in UK tap water conditions. Every care parameter here is sourced, and where I give an opinion I will tell you it is one.

We currently stock neon tetras in several group sizes — browse our neon tetra range to see what is available for tracked UK delivery.

Where neon tetras come from

The wild habitat of Paracheirodon innesi is the upper Amazon Basin — blackwater and clearwater tributaries across Peru, Colombia, and western Brazil^[1]. These are shaded forest streams with leaf litter, tangled roots, and tea-stained water that is soft, acidic, and dimly lit^[2].

Understanding this habitat explains almost everything about keeping them well. They want subdued lighting, dark surroundings, and stable soft water. A brightly lit bare tank with pale gravel is the opposite of what makes them comfortable, and you will see the difference in their colour and confidence within days of moving them into a properly set up aquascape.

In the wild they feed on tiny invertebrates, zooplankton, and insect larvae^[1]. They are adapted to a life of grazing on small particles in calm water — which is why oversized pellets get ignored and strong filter current stresses them out.

Tank setup

Size and layout

The minimum is 40 litres for a small group, but in my experience 60 litres is a much better starting point. A 40-litre tank with 10 neons, a heater, and a filter works — but it leaves no room for error on stocking, and the fish never look as confident as they do in something bigger.

The footprint matters more than height. Neon tetras are midwater schooling fish that swim horizontally, so a longer tank always beats a tall one. Dense planting around the back and sides with an open swimming lane through the centre gives you the best schooling effect.

Stocking suggestions

Water parameters

The accepted temperature range is 20-26 degrees C^[1], but I find they do best around 22-24 degrees. This is slightly cooler than many community tropicals, which is worth bearing in mind when choosing tank mates.

pH should sit between 5.0 and 7.5, with most captive-bred fish doing well around 6.2-7.0^[2]. Hardness ideally stays between 1 and 10 dGH^[2].

The honest truth is that stable parameters matter more than perfect ones. A tank that sits at pH 7.2 every single day is better for your fish than one that swings between 6.0 and 7.0 because you are chasing a number.

Filtration

Gentle to moderate flow is what you are after. A sponge filter is perfect for nano and breeding setups. For larger tanks, a compact internal or hang-on-back filter with an adjustable flow works well. These fish come from calm water — strong current pushes them around and wears them out.

Good filtration is also one of the simplest ways to prevent health problems. Most of the issues I see with neon tetras trace back to water quality, not disease in the traditional sense.

Substrate and decor

Dark sand or fine dark gravel makes the colours pop and helps the fish feel secure. I have kept neons over pale sand and over black — the difference is night and day. Against a dark background the blue stripe looks almost metallic, and the fish behave more boldly.

Add driftwood, leaf litter if you like the look, and plenty of fine-leaved plants. Java moss, Microsorum, Cryptocoryne, and floating plants all work. The goal is shade, cover, and that natural South American feel.

Lighting

Moderate is the sweet spot. Very bright lighting without plant cover makes them skittish and washes out the iridescent stripe. Subdued light — or strong light filtered through floating plants — brings out the glow. I run about 7 hours a day in my tetra tanks, sometimes 8 in mature planted setups.

Feeding

Neon tetras are easy to feed — they are unfussy omnivores that will eat most small prepared foods. The key word is small. Their mouths are tiny, and anything over about 1mm in diameter gets ignored or spat out.

Daily staple

A quality micro pellet or finely crushed flake works as the everyday diet. Feed once or twice a day, only what they can finish in about 30 seconds. I prefer sinking micro pellets over flakes because the tetras can pick at them as they drift through the midwater column, which is closer to their natural feeding style.

Supplementary foods

Two or three times a week I offer frozen daphnia, cyclops, or baby brine shrimp. This variety keeps condition up, supports the immune system, and brings out better colour than pellets alone. If you are conditioning fish for breeding, live baby brine shrimp and microworms are excellent.

Feeding tips

Overfeeding is the most common mistake with small fish. A tiny excess fouls the water fast in a lightly stocked tank. If there is food sitting on the bottom after a couple of minutes, you are feeding too much. In community tanks with faster species, make sure the neons are actually getting food — they can be outcompeted by more assertive feeders.

Newly arrived fish may eat lightly for a day or two. That is normal. Once settled, healthy neons should be keen feeders.

Appearance and varieties

The classic neon tetra is one of the most recognisable fish in the hobby. A slender, torpedo-shaped body with an iridescent blue-green stripe running from the nose to roughly the adipose area, and a vivid red band along the lower rear half^[1]. Adults typically reach 3.5-4 cm^[2].

Under subdued lighting the blue stripe takes on an almost electric metallic quality — this is the "neon" effect that gave the fish its common name. In a large school over dark substrate, the combined effect is genuinely striking.

Males tend to be slightly slimmer and straighter-bodied, while females are a touch deeper through the belly, especially when carrying eggs. The difference is subtle until you know what to look for, but it becomes obvious in a conditioned group.

You may also come across colour variants — the yellow neon tetra and albino forms being the most common. The wild-type colour pattern remains the most popular and the most stable in community settings.

How they compare to similar species

The question I get asked most is how they differ from cardinal tetras. The simple answer: cardinals have a red stripe that extends the full length of the body, while neons only show red on the back half. Cardinals also prefer warmer water (24-28 degrees versus 20-26 for neons). If your tank runs at 22-24 degrees, neons are usually the better choice. For warmer Amazonian setups, cardinals may be more at home.

Ember tetras are worth considering if you want something even smaller with warm orange tones rather than blue-red. Black neon tetras offer a more understated look. Green neon tetras (Paracheirodon simulans) are the smallest of the three Paracheirodon species and need very soft water.

Tank mates

Neon tetras are peaceful, non-territorial, and social^[2]. They are ideal community fish for tanks built around small, calm species.

Good companions

• Corydoras catfish — the classic pairing. They occupy different levels and share similar water preferences
• Other small tetras — ember tetras, glowlights, rummy-noses all work well
• Harlequin rasboras — peaceful midwater fish with compatible water needs
• Otocinclus — gentle algae grazers that will not bother anyone
• Cherry shrimp — coexist well in planted tanks, though very small shrimplets may be eaten
• Honey gouramis — a calm centrepiece fish for a South American or Asian community
• Dwarf cichlids (larger tanks only) — species like Apistogramma can work in a spacious, well-planted setup

Species to avoid

Anything with a mouth big enough to swallow them, and anything nippy or fast enough to outcompete them for food. Large angelfish will eat adult neons once they grow. Cichlids in general are a poor match. Serpae tetras can be nippy in smaller tanks. Boisterous barbs like tiger barbs create stress even if they do not directly attack.

The betta question

Many people ask about keeping neons with bettas. My honest answer is that it depends entirely on the individual betta. A calm one in a spacious, planted 60-litre tank may coexist happily. An aggressive one will make life miserable for both species. I would only try it with a solid backup plan and plenty of sight breaks in the tank.

Invertebrates

Adult shrimp generally coexist fine, but tiny shrimplets will be picked off. If you are serious about breeding shrimp alongside neons, a densely planted tank with lots of moss gives the babies a fighting chance. Nerite snails and other peaceful snails are completely safe.

Breeding

I will be upfront: breeding neon tetras is not a beginner project. The adults are easy to keep, but getting eggs to hatch and fry to survive takes proper preparation.

Setting up for spawning

You need a separate 20-30 litre tank with very soft water — under 4 dGH — and a pH around 5.5-6.0^[2]. Fine-leaved plants or spawning mops give the eggs somewhere to land. The tank should be dim, bordering on dark. These eggs are light-sensitive, and too much illumination kills them.

Condition a pair or small group on live and frozen foods for a week before introducing them to the breeding tank in the evening. Spawning usually happens in the early morning. The fish scatter small adhesive eggs among the plants^[2].

After spawning

Remove the adults immediately. They are not parental and will eat every egg they find. Keep the tank dark for the first 24 hours — I tape card over the sides. Eggs typically hatch within 24 hours, and the fry become free-swimming a few days after that.

Raising fry

Start with infusoria or a commercial liquid fry food, then move to newly hatched brine shrimp as they grow. Growth is slow and steady. Regular tiny water changes and careful feeding are essential. Many failures come from the water being too hard, the tank being too bright, or the first foods being too large.

Health and disease prevention

Healthy neon tetras are active, tightly schooled, alert to feeding, and show strong, vibrant colour. If your fish are pale, hiding, clamping their fins, or breathing rapidly, something is wrong.

Common problems

The biggest killer is poor water quality in immature tanks. Ammonia and nitrite poisoning account for more neon tetra deaths than any named disease. If your fish are newly added and struggling, test the water before reaching for medication.

Ich (white spot) is another common issue, especially after transport stress or temperature drops. Bacterial infections can follow fin damage from nipping tank mates. And then there is the dreaded neon tetra disease (Pleistophora hyphessobryconis) — a parasitic condition that causes fading colour, muscle wasting, and erratic swimming. There is no effective cure for neon tetra disease. Prevention through quarantine and sourcing healthy stock is the only real defence.

Prevention

The best medicine is good husbandry. Keep them in a proper school (less stress), maintain stable water parameters, feed a varied diet, quarantine all new arrivals for 2-4 weeks, and avoid aggressive tank mates that cause fin damage and chronic stress.

Quarantine protocol

Every new fish I bring in goes through a separate heated, filtered quarantine tank for at least two weeks. I watch for white spots, clamped fins, weight loss, and abnormal swimming. Only once they are feeding eagerly and looking healthy do they go into the display tank. This is especially important if you order fish online, because transport stress can suppress symptoms that emerge a few days later.

Behaviour

Neon tetra behaviour is one of the main reasons people fall for this species. In a proper school they are active midwater shoalers, moving as a coordinated group through the aquarium. When startled they tighten formation — it is genuinely mesmerising to watch.

Group size makes all the difference. A school of 6 hides, loses colour, and behaves nervously. A school of 20 patrols the tank confidently, stays visible, and displays far stronger colour. This is not just my opinion — it is a consistent observation across every fishkeeper I know who has upgraded from a small group to a proper school.

They are most active under moderate lighting with dark decor and plant cover. If your neons spend most of their time hiding behind the filter, the first things I would check are group size, lighting intensity, and whether there is a tank mate intimidating them.

UK delivery and acclimation

We ship live fish across the UK with insulated packaging and seasonal heat packs to protect against temperature drops during transit. Orders are dispatched Monday to Wednesday for tracked delivery, keeping time in the box as short as possible.

When your neon tetras arrive, float the sealed bag in your aquarium for 15 minutes to equalise temperature. Then drip-acclimate over 20-30 minutes — I use airline tubing with a loose knot to control the drip rate. This gradual transition is especially important for soft-water species. Do not dump the transport water into your tank — net the fish out and release them gently.

Newly arrived fish may hide and refuse food for the first day. That is completely normal after the stress of transport. Leave the lights off for the rest of the day, and by the following morning they should be exploring. If they are not feeding within 48 hours, test your water.

Why buy from us

We hold and observe all stock before dispatch. Every neon tetra we send out has been feeding on prepared foods, showing active schooling behaviour, and displaying clean, vibrant colour. We do not ship fish straight from the wholesaler — they are settled and ready.

Each order is packed specifically for small characins: insulated box, secure fish bags with oxygen, and heat packs in cooler months. Tracked delivery means your fish spend the minimum time in transit.

If you are building a display school, our group packs — browse our neon tetra listings — are the most practical way to establish a confident, natural-looking school from day one.

Answers to common questions

How many neon tetras should I keep?

At least 10, ideally 15-20. They are obligate shoaling fish that rely on group numbers for security. Small groups of 3-5 hide constantly and never show proper colour. The difference between 6 and 20 is not just aesthetic — it genuinely changes how the fish behave, feed, and interact with the rest of the tank.

What is the lifespan of a neon tetra?

Typically 3-5 years with good care^[1]. The main factors are water quality, tank maturity, and group size. Fish kept in stable, mature planted tanks with regular maintenance consistently outlive those in bare, recently set up systems.

What temperature do neon tetras need?

20-26 degrees Celsius^[1], with 22-24 being the sweet spot in my experience. They sit on the cooler end of the tropical range, which makes them slightly less suited to tanks running above 26 degrees for other species.

How do you breed neon tetras?

With patience and preparation. You need a separate dim tank, very soft acidic water (under 4 dGH, pH 5.5-6.0), conditioning with live foods, and the discipline to remove the adults immediately after spawning. See the breeding section above for the full method.

What are good tank mates for neon tetras?

Corydoras are the classic pairing. Other small tetras like ember tetras and cardinal tetras, harlequin rasboras, otocinclus, and cherry shrimp all work well. Avoid anything large, fast, or nippy.

Can neon tetras live with bettas?

It depends on the betta. A calm individual in a spacious planted tank of 60 litres or more may ignore them entirely. An aggressive one will not. I would only try this combination with a backup plan in place. Read our betta care guide for more on betta temperament.

Why are my neon tetras pale or losing colour?

Stress. The usual causes are ammonia or nitrite in the water, groups that are too small, overly bright lighting, or intimidating tank mates. Test your water, check your group size, and add more plant cover. If the water is clean and the group is large enough, look at whether another fish in the tank is causing problems.

What do neon tetras eat?

Micro pellets or finely crushed flake as a daily staple, with frozen daphnia, cyclops, or baby brine shrimp as supplements two to three times a week. Keep particle size small — under 1mm — and feed only what they finish in 30 seconds.

Do neon tetras need a heater in the UK?

Yes. UK room temperatures drop below 20 degrees for most of the year, and neon tetras need a consistent 20-26 degrees. An adjustable heater with a thermostat is essential — I would not rely on preset models.

What is the difference between neon tetras and cardinal tetras?

The red stripe is the quickest way to tell. On neons it covers the back half of the body; on cardinals it runs the full length. Cardinals also prefer warmer water (24-28 degrees) and grow slightly larger. If your tank sits around 22-24 degrees, neons are the better fit.

Are neon tetras good for beginners?

Yes, with one caveat — the tank must be properly cycled first. If you give them a mature, stable tank, a group of 10 or more, and regular water changes, they are genuinely one of the easiest tropical fish to keep. Check our first tropical tank guide if you are setting up your first aquarium.

What size tank do neon tetras need?

40 litres minimum, but 60 litres is a much more practical starting point. A 40-litre tank limits you to a single school with no room for companion species. At 60-90 litres you can keep 15-20 neons with bottom dwellers, which is where the species looks and behaves at its best.