6 × Neon Dwarf Rainbowfish (Melanotaenia praecox)

Choose an active Mamberamo shoaler

The Neon Dwarf Rainbowfish (Melanotaenia praecox) is a freshwater rainbowfish in the family Melanotaeniidae from the Mamberamo River in northern Irian Jaya, Indonesia. FishBase records a maximum of 5 cm standard length. This pack suits a keeper prepared to maintain a proper shoal in a mature, filtered and planted community aquarium with generous open swimming room.

Although compact, this is an active fish rather than a choice for a very small display. FishBase gives a minimum aquarium size of 80 cm, while the Seriously Fish species profile recommends at least 60 × 30 × 30 cm and approximately 54 litres. Plan around the longer 80 cm figure, retain at least a 30 cm front-to-back dimension and do not go below the approximately 54-litre volume.

Keep routine aquarium water at 23–27°C, pH 6.8–7.5 and 5–12 dGH. These targets are the overlap of the Seriously Fish profile and OATA’s group-level rainbowfish guidance. The overlap gives a practical target for daily care while remaining inside the species profile.

Know what the pack includes

One purchase supplies a pack of six live Neon Dwarf Rainbowfish. The pack already meets the lower end of the shoal recommended by Seriously Fish, which says this species does far better in a group of at least six to eight and preferably more. If the aquarium can support a larger shoal after all existing livestock and filtration capacity are considered, eight or more gives the fish a broader social group.

Plan the aquarium for six adult fish. Judge the aquarium by the adult planning figures and activity level rather than assuming that the fish will remain at their arrival size. The aquarium and biological filter must be ready for all six fish together.

Sex is guaranteed only when the selected option explicitly states male or female. This 6 × Neon Dwarf Rainbowfish listing has no sex-guaranteed option. Mature males are larger and brighter than females and develop a much deeper body as they grow, but appearance in a gallery image does not determine which sexes will be supplied.

The gallery images are representative of this type of animal rather than photographs of the exact animal supplied, so colours can look slightly different from the live animal. Use the images to recognise the general body form and markings, not to select an individual fish or infer its sex.

Before adding the pack, account for the six fish in the aquarium’s total stocking plan. OATA advises increasing aquarium populations slowly because the beneficial bacteria in the filter must process the extra waste created by more fish and feeding. Avoid combining this pack with several other livestock additions at the same time.

Plan the aquarium around the adult size

Plan every part of the care around an adult size of 5 cm standard length. Build around the species’ activity and the stated aquarium dimensions rather than using body length alone to justify a smaller tank.

Meet both space recommendations

• Length: choose an aquarium at least 80 cm long to meet the FishBase minimum aquarium-size figure.
• Footprint: retain a base of at least 60 × 30 cm, following the Seriously Fish recommendation.
• Volume: do not plan below approximately 54 litres; a longer aquarium will commonly hold more, depending on its actual dimensions.
• Swimming room: preserve open water between planted areas so the shoal can move together and males have room to display.
• Cover: use plants around parts of the aquarium rather than filling the entire swimming route.

A worked check is straightforward. An aquarium that holds approximately 54 litres but is shorter than 80 cm meets the Seriously Fish volume example but not the FishBase length figure. An 80 cm aquarium with a narrow footprint below 30 cm front to back misses the recommended width. Choose a design that satisfies length, footprint and volume together.

Do not plan a smaller temporary aquarium around the fish’s arrival size. The pack is six active shoalers from the start, and their social group, swimming route, filtration load and adult planning dimensions apply from the day they enter the aquarium.

Build a planted layout without losing swimming room

Create a planted aquarium with open spaces between groups of vegetation. Seriously Fish recommends a heavily planted setup but also calls for clear swimming areas and display space. The useful balance is cover around the edges or in defined islands, with an uninterrupted route through the aquarium for the shoal.

Arrange the space by function

• Planting: provide substantial live planting where possible. If live plants are not used, add plastic plants and suitable ornaments, such as plant pots or model caves, so the fish have shelter.
• Open water: leave broad gaps between planted areas instead of creating a continuous wall of stems.
• Light diffusion: use floating plants to soften bright conditions. Seriously Fish notes that this species does not appreciate bright conditions.
• Substrate: aquarium gravel or sand fits OATA’s rainbowfish setup guidance.
• Shelter: plants and suitable ornaments can provide cover, particularly when fish are settling or moving away from activity.

Check the layout from end to end before the fish arrive. If decorations force the shoal through a single narrow channel, remove or regroup some items. If the tank is almost entirely bare, add planted cover without blocking the main route. The aim is not maximum decoration; it is a useful combination of refuge, softened light and continuous swimming room.

Watch how the group uses the aquarium after introduction. Regular movement through the open areas and the ability to move into cover show that both functions are accessible. Persistent crowding in one small area calls for checks of water quality, lighting, neighbouring fish and whether the layout provides enough usable space.

Keep the planted design compatible with routine maintenance. Leave enough access to siphon waste from the substrate, inspect the fish and check filter inlets for blockage. A layout that cannot be cleaned reliably will work against the high water quality this rainbowfish needs.

Hold routine water inside the shared range

Keep the aquarium at 23–27°C, pH 6.8–7.5 and 5–12 dGH. This is the overlap of the Seriously Fish values for Melanotaenia praecox and OATA’s rainbowfish figures, so each routine target stays inside both sets of guidance.

Measure the aquarium rather than relying on a heater setting or the water’s appearance. Use the same test method consistently so changes are easier to recognise. Our guide to understanding aquarium water chemistry explains what the main readings mean, and the water matcher can help compare measured values with the stated range.

A single reading inside the range is only a starting point. Check whether the aquarium remains there over time, particularly before livestock is introduced and after the population changes. If temperature, pH or hardness sits outside the target, resolve that difference before adding the pack rather than expecting the fish to bridge incompatible conditions.

For an aquarium of approximately 54 litres in a room around 20°C, Seriously Fish estimates a heater rating of roughly 75–100 W. That wattage is tied to those stated conditions. Choose equipment for the aquarium’s actual volume and room temperature, then confirm the result with a thermometer.

Keep ammonia and nitrite at zero. OATA warns that even small amounts can stress rainbowfish, while nitrate should not exceed 20 mg per litre above the normal tap-water level. When a reading moves in the wrong direction, test again carefully, check filtration and feeding, and correct water quality before adding more livestock.

Establish biological filtration before adding the pack

Use a well-established biological filter before the six fish arrive. The RSPCA explains that fish release toxic ammonia; beneficial bacteria in a working biological filter convert it first to nitrite and then to the safer nitrate. A filter is therefore part of the life-support system, not simply a way to make the water look clear.

Seriously Fish recommends four to five aquarium turnovers per hour for this species. In its approximately 54-litre example, that corresponds to a filter rated around 215–270 litres per hour. Use that rating only for an aquarium around the example volume; choose equipment suited to the actual volume while retaining the stated turnover target.

Confirm readiness before introduction

1. Set up the aquarium, heater and filter before the fish are due.
2. Follow the first tropical aquarium setup guide to prepare and mature the system.
3. Test ammonia and nitrite and proceed only when both read 0 mg per litre.
4. Confirm that temperature, pH and hardness are inside the routine care range.
5. Check that the filter is running freely and that its inlet is not obstructed by plants or decoration.
6. Review existing livestock and ensure the aquarium can absorb a six-fish addition without overcrowding.

Do not judge maturity by elapsed time alone. The relevant test is whether the biological filter can maintain zero ammonia and zero nitrite while the aquarium is operating normally. Clear water can still contain dissolved ammonia or nitrite, so visual inspection cannot replace testing.

The pack creates one defined stocking event involving six fish. OATA advises increasing fish populations slowly because bacterial capacity must rise as waste and feeding increase. Prepare for the whole pack, avoid unrelated additions at the same time and monitor the aquarium after introduction.

Feed one controlled, varied meal each day

Feed a good-quality flake or granule as the regular dried food. Melanotaenia praecox is described by Seriously Fish as an unfussy omnivore that accepts dried, frozen and live foods. OATA recommends small live or frozen items such as daphnia, small bloodworm or tubifex to add variety.

Offer only what the shoal can eat within a few minutes, once a day. Keep to that single daily meal. Watch the whole group during that short period so the portion is judged by what all six fish consume, not by the fastest fish taking the first pieces.

Use variety without increasing the portion

• Regular food: a good-quality flake or granule.
• Variety: small daphnia, small bloodworm or tubifex in live or frozen form.
• Frequency: one feeding period per day.
• Portion: only the amount eaten within a few minutes.
• Colour and condition: regular feeds of live foods will help the fish show their best colours.

Variety means rotating suitable foods within the daily allowance, not adding several full meals. Uneaten food breaks down and releases waste into the water, increasing pressure on the biological filter. If food remains after a few minutes, remove the leftovers and reduce the next portion.

A reduced interest in food is a health and water-quality warning rather than a reason to keep adding different foods. Check ammonia, nitrite, temperature and the fish’s breathing and swimming behaviour. Resume a controlled amount only after considering why feeding behaviour changed.

Keep each item appropriately small for a compact rainbowfish. Choose small live and frozen foods that the shoal can eat promptly rather than large pieces.

Maintain the aquarium every week

At least once every week, carry out a 25% partial water change. OATA recommends this frequency and amount for rainbowfish, together with weekly water testing. Use the routine to remove solid waste, check equipment and compare current readings with the aquarium’s normal pattern.

Follow a repeatable maintenance sequence

1. Test ammonia, nitrite and nitrate before changing water so the readings show the aquarium’s condition.
2. Inspect the fish for changes in breathing, swimming, colour, appetite, body condition, fins and scales.
3. Siphon solid waste from accessible areas of gravel or sand while removing 25% of the water.
4. Treat replacement tap water with a conditioner that removes chlorine or chloramine before adding it.
5. Bring the aquarium back to its normal operating level without moving temperature, pH or hardness outside the routine range.
6. Check the filter for restricted flow or blockage.

If the filter needs cleaning, rinse its media lightly in aquarium water removed during the partial water change. Do not run it under the tap. Chlorine or chloramine may kill part of the beneficial bacterial population established in the media, reducing the filter’s ability to process waste.

Keep to that weekly routine.

Compare nitrate with the normal tap-water level because OATA expresses the limit as no more than 20 mg per litre above that baseline. For example, if tap water measures 10 mg per litre nitrate, the stated ceiling in the aquarium is 30 mg per litre. Ammonia and nitrite remain at zero regardless of the tap-water nitrate reading.

Record results if patterns are difficult to remember. A sequence of readings makes gradual deterioration easier to spot than isolated tests and helps connect changes with feeding, filter flow or livestock additions.

Receive and acclimatise the fish carefully

Be present to receive the parcel because live fish must not be left unattended. Tropical Fish Co hand-bags fish in pure oxygen, uses an insulated poly box and adds a heat pack when the weather calls for it. A licensed live-animal courier carries the parcel.

Before delivery, confirm that the aquarium is operating at 23–27°C, pH 6.8–7.5 and 5–12 dGH, with ammonia and nitrite at 0 mg per litre.

Follow the arrival sequence in order

1. Receive the sealed parcel and start filming before it is opened. Keep the outer box visible and record continuously from the sealed parcel onward.
2. Open and inspect it the same day. Continue filming as the parcel is opened and show the fish while they remain inside the sealed bag.
3. Float the bag for 20–30 minutes before releasing the fish. Let the bag float for 20–30 minutes so the fish acclimatise slowly.
4. Release the fish without pouring bag water into the aquarium.
5. Keep the video and order number. For a Live Arrival Guarantee claim, notify us the same day with the order number and continuous unboxing video.

The continuous video should show the parcel still sealed, the outer box, the opening and the fish still in the sealed bag before anything is disturbed. Filming every delivery from the sealed parcel onward preserves the complete sequence if a claim is needed.

Read the current delivery and Live Arrival Guarantee policy before the delivery day. It contains the policy conditions and current claim process. The aquarium must already be mature and suitable; arrival day is not the time to begin establishing filtration or adjusting basic water chemistry.

Act promptly when behaviour or condition changes

Learn the group’s normal swimming, colour, feeding response and breathing pattern, then investigate any clear change. OATA identifies altered swimming, colour, temperament, breathing, appearance, body condition and feeding as signs that deserve attention.

Water testing comes first because ammonia and nitrite are toxic and rainbowfish can be stressed by small amounts. Confirm both are at 0 mg per litre, check nitrate against the tap-water baseline and verify the routine temperature, pH and hardness.

Do not use increased feeding to compensate for reduced body condition until the cause has been considered. Extra uneaten food can worsen water quality and increase the load on the filter. Likewise, a partial water change should follow measured conditions and the established maintenance routine rather than replacing careful observation.

Inspect all six fish. A change affecting several fish at the same time points towards a shared aquarium factor that needs immediate checking, while one affected individual still requires close attention. Keep observations factual: note what changed, when it was seen and the test readings taken at the time.

Screen companions by size, activity and water needs

Choose similarly-sized community fish whose water needs overlap with 23–27°C, pH 6.8–7.5 and 5–12 dGH. Seriously Fish describes Melanotaenia praecox as very peaceful and names similarly-sized rainbowfish, characins, danios, barbs, dwarf cichlids, freshwater gobies and catfish such as Corydoras as good tank-mate categories.

Those names begin the assessment rather than completing it. Check the candidate animal’s adult size, social needs, temperament, aquarium-space requirement and water range. The aquarium must also have enough capacity for the six rainbowfish and the proposed companions without compromising the swimming route or filtration.

Use a clear screening rule

• Suitable to assess: similarly-sized rainbowfish, characins, danios, barbs, dwarf cichlids, freshwater gobies and Corydoras.
• Avoid: timid fish and fish much smaller than the rainbowfish. OATA advises that active rainbowfish should not be mixed with animals in those categories.
• Check water: the companion’s normal care range must overlap the aquarium’s routine values.
• Check space: retain the required shoal and open swimming room after the companion group is included.
• Check behaviour: observe for persistent chasing, increased hiding, damaged fins or interrupted feeding.

Peaceful behaviour does not make every community species compatible. Activity can unsettle timid animals even without predatory or overtly aggressive behaviour. A much smaller fish also falls outside OATA’s recommended mix for active rainbowfish.

For invertebrates or any fish category not named above, apply the same screening process and accept that the outcome depends on the exact candidate. Check adult size, water requirements, behaviour and space before combining them. If the match remains unclear, contact us for a stocking assessment with the aquarium dimensions, water readings and current livestock list.

Make the complete stocking decision before purchase

Plan the whole community on paper before adding the pack. Begin with six Neon Dwarf Rainbowfish, reserve their open swimming route and aquarium dimensions, then add the full adult requirements of every existing and proposed companion. This prevents a peaceful-looking list from exceeding the aquarium’s space or filtration capacity.

Work through common decisions

A similarly-sized characin shares the water range: it belongs to a category named by Seriously Fish, so continue by checking its own group size and the total aquarium capacity. Do not count one social species as part of the other species’ shoal.

A danio fits the water but leaves no open swimming room: the stocking plan fails on space even though the animal category is named as a good tank mate. Choose a larger aquarium or a smaller total community.

A candidate fish is timid or much smaller: do not mix it with this active rainbowfish. OATA places those combinations outside its compatibility guidance for active rainbowfish.

A Corydoras species is being considered: Seriously Fish names Corydoras as a suitable catfish category, but the exact species must still fit the water, social and space plan.

An invertebrate is being considered: use its exact adult size, water values and behaviour to assess the match. Do not assume that every freshwater invertebrate is automatically compatible.

After introduction, watch whether every group can feed normally and use its intended space. Increased hiding, changed colour, persistent chasing, damaged fins or interrupted feeding are reasons to reassess the combination and test the water. Do not respond by adding more livestock.

The six-fish pack meets the lower end of the recommended shoal for this species. If expanding towards eight or more, confirm that filtration and total stocking capacity can support the extra fish before increasing the group. A larger shoal is beneficial only when the aquarium remains suitable for all its inhabitants.

Answer common buyer questions

How big do Neon Dwarf Rainbowfish get?

FishBase records the Neon Dwarf Rainbowfish at a maximum of 5 cm standard length. Plan the aquarium around that adult figure, the activity of a six-fish shoal and the stated aquarium dimensions rather than the fish’s arrival size.

What size aquarium do 6 × Neon Dwarf Rainbowfish need?

Use an aquarium at least 80 cm long, retain a base of at least 60 × 30 cm and do not go below approximately 54 litres. FishBase gives the 80 cm minimum, while Seriously Fish gives at least 60 × 30 × 30 cm and approximately 54 litres.

How many Neon Dwarf Rainbowfish should I keep together?

Keep at least six Neon Dwarf Rainbowfish together, preferably eight or more. Seriously Fish says they do far better in a shoal of at least six to eight, while this purchase supplies a pack of six.

Is this rainbowfish suitable for a beginner?

Choose it once you have a mature, filtered aquarium at least 80 cm long, room for a shoal of at least six and a weekly routine of water testing and a 25% water change. It is not a suitable first addition to an uncycled aquarium.

What do Neon Dwarf Rainbowfish eat?

Feed Neon Dwarf Rainbowfish a good-quality flake or granule, with small live or frozen daphnia, small bloodworm or tubifex for variety. Offer only what the shoal eats within a few minutes, once a day.

What temperature and pH does this fish need?

Keep it at 23–27°C, pH 6.8–7.5 and 5–12 dGH. These routine values are the overlap of the Seriously Fish species profile and OATA’s rainbowfish guidance; ammonia and nitrite must remain at 0 mg per litre.

Is it aggressive or likely to nip fins?

Seriously Fish describes it as very peaceful. Treat activity as the main compatibility issue: avoid timid or much smaller fish, and investigate persistent chasing, increased hiding, damaged fins or interrupted feeding.

Which kinds of animals can it live with?

Assess similarly-sized rainbowfish, characins, danios, barbs, dwarf cichlids, freshwater gobies and catfish such as Corydoras. Each exact candidate must also match the water, adult space, social and temperament requirements; invertebrates require an individual assessment.

How do 6 × Neon Dwarf Rainbowfish arrive alive in the UK?

The six fish are hand-bagged in pure oxygen, placed in an insulated poly box with a heat pack when the weather calls for it and carried by a licensed live-animal courier. Be present, film continuously from the sealed parcel, open and inspect it the same day, float the bag for 20–30 minutes and retain the video and order number for the Live Arrival Guarantee process.

Consult the care references

• FishBase: Melanotaenia praecox — identity, family, distribution, recorded length, environmental temperature and aquarium group and length guidance.
• Seriously Fish: Melanotaenia praecox — aquarium dimensions, water conditions, feeding, layout, behaviour and named tank-mate categories.
• OATA: How to look after rainbowfish — group care for water quality, feeding, maintenance, social keeping and compatibility screening.
• RSPCA aquarium environment guidance — biological filtration and the aquarium nitrogen cycle.
• Tropical Fish Co delivery and Live Arrival Guarantee policy — packing, receipt, unboxing video, acclimatisation and claim steps.