Easy
Banded Rainbowfish (Melanotaenia trifasciata)
24–30°C · pH 7–8.5 · 200L
£7.99
New Guinea Red Rainbowfish is a Lake Sentani endemic reaching 12 cm standard length. Keep at least six in a mature 120 cm / roughly 250 L+ hard-water aquarium with open swimming space, strong oxygenation and a varied omnivorous diet.
Glossolepis incisus
New Guinea Red Rainbowfish are a shoaling species — they need 6+ to feel safe and show their full colour.
New Guinea Red Rainbowfish is a Lake Sentani endemic reaching 12 cm standard length. Keep at least six in a mature 120 cm / roughly 250 L+ hard-water aquarium with open swimming space, strong oxygenation and a varied omnivorous diet.
Maintain these water conditions for optimal health and vibrant colors
New Guinea Red Rainbowfish (Glossolepis incisus) is a large, active shoaling rainbowfish endemic to Lake Sentani in Indonesian New Guinea. Mature males can develop a deep red body, while females and younger fish are usually more olive, bronze or yellow. Colour takes time, social confidence and suitable care; a juvenile dispatch size cannot guarantee adult sex or intensity.
This is not a small general-community fish. FishBase records up to 12 cm standard length and recommends groups of at least five with a minimum aquarium length of 100 cm. For long-term welfare, use six or more in a 120 cm aquarium of roughly 250 litres or larger, with open swimming space, mature filtration, strong oxygenation and a secure lid.
| Accepted scientific name | Glossolepis incisus Weber, 1907 |
|---|---|
| Family | Melanotaeniidae |
| Natural range | Endemic to Lake Sentani, Indonesian New Guinea |
| Published maximum | 12 cm standard length |
| Social group | At least six; a larger mixed group where space permits |
| Practical aquarium | 120 cm long and around 250 L+ for a group |
| Practical temperature | 24-28 C; published Lake Sentani record 29-30 C |
| Practical pH | 7.0-8.2 |
| Hardness | 9-19 dGH |
| Temperament | Generally peaceful but fast, active and competitive at food |
| Diet | Quality rainbowfish pellets or flakes with varied frozen or trusted live foods |
| Swimming level | Middle and upper open water |
The practical temperature range is a conservative aquarium target, while the 29-30 C figure is the published natural-water record shown by FishBase. At high temperature, dissolved oxygen falls and metabolism rises, so oxygenation and waste control become even more important. Do not change temperature abruptly to imitate a single field reading.
Glossolepis incisus is an accepted species in FishBase and the GBIF taxonomic backbone. New Guinea Red Rainbowfish, Red Rainbowfish and Salmon-Red Rainbowfish are common trade names. The scientific name is the reliable identity anchor because “red rainbowfish” can be used loosely for other species and colour forms.
FishBase carries an Endangered IUCN assessment for the wild species, assessed in 2019. A shop listing must not turn that status into a wild-caught claim. This product is not represented as a locality-certified or wild-collected fish unless batch documentation specifically proves it. Responsible captive keeping should maintain accurate species identity and avoid releasing aquarium fish into the environment.
Lake Sentani lies in a hilly region of Indonesian New Guinea. The species is restricted to this lake system, which makes the geographic identity important. In the aquarium, the useful lessons are open swimming length, warm oxygenated water, harder alkaline chemistry and planted or structured margins rather than a cramped densely decorated tank.
Create open central water with plants, wood or smooth rock around the back and sides. The fish need room to accelerate, turn and display. A wall of hardscape may look dramatic but can reduce the useful length and create collision points for a fast group.
FishBase gives 12 cm standard length, measured without the tail fin. Total visual length can therefore be greater. Adult males also become deep-bodied, so filtration and turning room must account for mass as well as length.
A group of six adult fish is a substantial bioload. Planning from juvenile shop size can lead to an aquarium that appears adequate for a few months and then becomes crowded as the fish deepen and activity increases.
| Stage | What changes | Keeper priority |
|---|---|---|
| Small juvenile | Subdued colour, small mouth, rapid growth | Fine food, intake protection and frequent body checks |
| Larger juvenile | Stronger swimming and food competition | Multiple feeding points and full adult aquarium |
| Maturing group | Sex differences and displays develop | Balanced group, open water and observation |
| Adult | Deep body, strong colour and high activity | 120 cm+ swimming length, oxygen and filtration capacity |
The size selector describes approximate dispatch length, not adult size or sex. A 4.5-5.5 cm fish needs appropriately sized food and close observation. A 6-7 cm or 7-8 cm fish still requires the same group and adult aquarium.
Colour at dispatch is not a promise of final appearance. Males develop stronger red with maturity, condition and social display, while females are generally less red. Young males can resemble females, and stressed fish may temporarily lose colour.
Live measurements are approximate because fish do not hold still against a ruler. Choose a variant for compatibility with the established group, not because a smaller fish appears suitable for a temporary tank.
Keep at least six. FishBase notes groups of five or more; using six provides a clear practical minimum and allows more natural movement and display. A larger group can distribute attention and create a more confident shoal when aquarium size and filtration allow.
Do not keep one as a centrepiece. A solitary fish may become nervous, hide, pace or fail to display natural colour. Two or three fish do not create the same social environment and can concentrate male pursuit on one individual.
| Group plan | Assessment | Main issue |
|---|---|---|
| Single fish | Not recommended | No shoal security or normal display context |
| Pair or trio | Not recommended | Attention and chasing can focus on one fish |
| Six | Practical minimum | Needs full adult space and filtration |
| Eight to twelve | Excellent in a larger aquarium | Bioload and swimming length increase substantially |
A mixed-sex group can show attractive display behaviour, but exact sex ratios cannot be guaranteed at juvenile sizes. A female-biased group can reduce concentrated male attention. Monitor actual behaviour rather than relying on a fixed ratio.
Juvenile groups may be difficult to sex. As males mature, colour and body depth develop and morning display becomes more obvious. If several males focus on too few females, courtship can become relentless even without injury. More swimming space, planted margins and a female-biased composition can reduce pressure.
Do not remove every less-colourful fish in pursuit of an all-red display. Females provide the social context for male display and are part of a stable mixed group. An all-male group may work in a very large aquarium, but display and dominance still require observation.
| Observation | Possible meaning | Response |
|---|---|---|
| One male colours strongly while others remain pale | Dominance or maturity difference | Check feeding and avoid assuming every pale fish is female |
| One female is chased continuously | Sex ratio or space is inadequate | Increase separation and adjust the group only with quarantine capacity |
| Several fish remain at one end | Flow, bullying or exposure problem | Inspect the full swimming lane and water conditions |
| Group displays and then resumes normal swimming | Healthy social interaction may be occurring | Continue monitoring body condition |
A settled group uses the middle and upper water, turns together and spreads across the open lane. Males may intensify colour and display side-on, especially around morning light and feeding. Brief pursuit can occur, but every fish should retain access to open water, cover and food.
Constant dashing into glass, hiding behind the filter, clamped fins or refusal to join the group is not normal shoaling. Check reflections, aquarium length, current, water, group size and aggression. Fast movement does not always mean the fish are thriving; panic and normal activity look different over time.
Use gradual lighting transitions. An abrupt bright light can startle a fast shoal into the lid or hardscape. Room light before and after aquarium light provides a gentler change.
Use a 120 cm-long aquarium and around 250 litres or more for a group. FishBase gives a 100 cm minimum length, but the larger practical recommendation provides better adult turning room, territory dilution and water stability.
Length matters more than height alone. A tall 250-litre aquarium with a short footprint may offer less useful swimming distance than a lower, longer tank. Use the tank-volume tool to calculate filled volume after substrate and decor, then judge the longest unobstructed lane.
The cycle tracker can organise evidence. A large aquarium is not automatically cycled, and adding a full shoal at once creates a significant waste increase.
Quarantine the intended group together where space permits so social and disease observations can be made before the display aquarium. The quarantine filter must be mature and capable of handling active juveniles; a bare uncycled tub is not adequate.
When the main aquarium is ready, adding the whole social group can be better than leaving one or two fish alone for weeks, but it creates an immediate bioload increase. Confirm filter capacity, feed lightly at first and test ammonia and nitrite daily after introduction.
Use sturdy plants along the back and sides, leaving a broad central lane. Vallisneria, Java fern, Anubias and other species suited to harder alkaline water can work. Floating plants may provide security, but do not block the entire surface or reduce oxygen exchange.
Make wood and rock stable and smooth. Fast fish can collide with sharp projections during feeding or display. Avoid narrow gaps that trap a deep-bodied adult. Keep enough open foreground to inspect every fish's body condition and fins.
Rainbowfish can jump when startled, displaying or chasing food. Fit a secure lid across the entire aquarium and close gaps around pipes and cables. A cover glass must be supported safely and should not obstruct gas exchange.
Leave turning space around hardscape. Pointed branches facing the open lane can cause injury when the group accelerates. Place heaters and intakes where a panicked fish cannot become trapped behind them.
Feed across a broad area rather than dropping everything against one corner. This reduces collisions and gives slower fish a chance to eat. If fish strike the lid at every meal, reduce excitement by changing the feeding method and checking whether portions are too infrequent.
Use a practical pH of 7.0-8.2 and hardness around 9-19 dGH, reflecting the alkaline mineral-rich values published for the species. Test source water before purchase. If tap water is much softer, create a repeatable preparation method rather than adding unmeasured minerals directly to the aquarium.
| Ammonia | 0 mg/L |
|---|---|
| Nitrite | 0 mg/L |
| Nitrate | Controlled through stocking, feeding and measured water changes |
| Practical temperature | 24-28 C |
| Practical pH | 7.0-8.2 |
| Hardness | 9-19 dGH |
Use the water matcher to compare source water. Stability matters more than hitting an exact midpoint, but chronically unsuitable soft acidic conditions should not be ignored.
Start with weekly partial water changes, then adjust the amount and frequency from nitrate, feeding and total stocking. Match replacement temperature, pH and hardness closely. A large sudden change in mineral content can be stressful even when the new value looks ideal on paper.
Do not replace all filter media, deep-clean the substrate and alter hardness on the same day. Stagger major tasks so biological stability and chemistry are not disrupted together.
Evaporation removes water but leaves minerals behind, so hardness and dissolved solids can rise between water changes. Top-up water restores volume but does not remove accumulated minerals or nitrate. Continue proper partial water changes.
During hot weather, a fan increases evaporation. Measure pH and hardness if top-ups become frequent. Use a consistent source and never add mineral salts without knowing the current and replacement-water values.
Maintain 24-28 C as the practical aquarium range. FishBase reports natural water at 29-30 C, but sustained heat reduces dissolved oxygen and increases metabolism. A mature captive group can be managed safely without forcing the tank to the highest field reading.
Provide strong gas exchange through surface movement and distributed flow. The fish should swim actively without gasping, crowding the outlet or hanging at the surface. Warm water, heavy feeding and a crowded shoal can combine into an oxygen emergency quickly.
During a heatwave, measure the aquarium, increase safe aeration, reduce unnecessary lighting heat and feed conservatively. Do not add loose ice or create a sudden cold shock.
Use an external or high-capacity internal filter sized for the adult bioload, with prefiltration where useful. Flow should circulate oxygen and collect waste across the long tank without creating one narrow jet that exhausts the group.
Position outlets to create broad movement and quieter planted margins. Clean mechanical media when flow falls, using removed aquarium water where appropriate. Do not replace all mature biological media at once.
Filter turnover numbers are not the only measure. Observe waste accumulation, oxygen, nitrate and swimming behaviour. A filter can move a great deal of water while leaving dead spots behind hardscape.
Use quality rainbowfish pellets, small cichlid granules or flakes as a complete base. Rotate frozen or trusted live foods such as daphnia, cyclops, brine shrimp, mysis and suitable insect larvae. Include plant-derived ingredients rather than feeding rich animal foods exclusively.
| Food | Role | Use |
|---|---|---|
| Complete rainbowfish pellet or flake | Daily nutritional base | Choose a size all group members can take |
| Daphnia or cyclops | Small-invertebrate variety | Rotate in modest thawed portions |
| Brine shrimp or mysis | Conditioning and enrichment | Use as part of a varied diet |
| Trusted live insect larvae | Natural hunting behaviour | Use only from a safe source |
| Plant-inclusive prepared food | Omnivorous balance | Keep in the weekly rotation |
Feed adults once or twice daily in amounts cleared promptly. Spread food along the surface so dominant fish cannot intercept everything. Remove leftovers and reduce portions if nitrate climbs or bodies remain excessively rounded.
There is no universal pinch or pellet count because food density and fish size vary. Begin with a measured amount, watch the entire group and adjust the next meal. The target is active feeding without food reaching hidden corners and decaying.
| Body or feeding sign | Possible cause | First response |
|---|---|---|
| Dominant male intercepts most surface food | Single feeding point | Spread food across the aquarium |
| Small fish remains hollow | Competition or illness | Observe it eat and assess quarantine |
| Food reaches substrate uneaten | Portion too large or particle unsuitable | Remove waste and reduce the next portion |
| All fish remain excessively rounded | Chronic overfeeding | Reduce portions and review nitrate |
| Group refuses a familiar food | Stress or water problem | Test water before offering repeated alternatives |
Conditioning for colour or spawning should increase food variety, not simply quantity. Rich frozen food without plant-inclusive prepared nutrition and matching maintenance can lead to obesity and poor water quality.
Watch the slowest fish, not only the most colourful male. Every individual should maintain an even body profile and approach food. A subordinate fish can lose weight while the group appears energetic.
Use several feeding points and vary particle size. Persistent hollow body shape, spitting, isolation or refusal to feed requires water testing and health investigation. Sudden swelling is not normal growth.
This species is generally peaceful but very active. Choose robust companions that share warm alkaline water and can feed confidently without nipping fins. Suitable rainbowfish of comparable size, larger peaceful barbs and sturdy catfish may work in a sufficiently large aquarium.
| Companion | Assessment | Condition |
|---|---|---|
| Comparable rainbowfish | Often suitable | Provide each species with its proper group and enough swimming length |
| Larger peaceful barbs | Possible | Avoid known fin-nippers and check temperature |
| Robust bottom catfish | Possible | Match water and provide floor area and deliberate food |
| Slow long-finned fish | Avoid | May be stressed or outcompeted by constant activity |
| Tiny timid fish | Avoid | Feeding pressure and stress |
| Large aggressive cichlids | Avoid | Bullying and injury risk |
Use the tank-mates tool as an initial screen, then assess adult size, group needs, swimming speed and water chemistry. A peaceful label does not guarantee that a slow fish will thrive beside a fast shoal.
These examples illustrate decision-making rather than fixed recipes. The final answer depends on the aquarium's dimensions, source water, filter and individual species.
A group of six to eight Red Rainbowfish can be the main feature, with planting at the margins and open central water. This plan makes group behaviour and feeding easy to assess and avoids diluting the display with several undersized shoals.
In a substantially larger and longer aquarium, another robust rainbowfish species may be possible. Keep a full group of each, avoid hybridisation risk and ensure both have compatible chemistry. Several pairs are not equivalent to proper shoals.
Sturdy catfish can use the lower zone where water and temperature match. They still need their own floor area and food. Watch that the fast upper group does not consume every sinking item before it reaches the bottom.
Disc-shaped, long-finned or timid fish may be stressed by constant movement even if no biting occurs. Food competition alone can make the combination fail. Choose companions for pace as well as aggression.
Closely related rainbowfish can hybridise in aquariums. Keep species identity records and do not distribute mixed offspring as pure stock. If breeding is intended, use a species-focused setup and verify both parents.
Juveniles may be difficult to identify by colour alone. Label grow-out tanks, keep source records and avoid mixing fry from several species. Accurate captive populations matter especially for a wild species with a restricted endangered range.
Mature males can become vivid red and deeper-bodied. Females are generally more olive, bronze or yellow and may remain slimmer. Colour depends on maturity, diet, background, water, health and social confidence.
Do not use colour-enhancing food to replace balanced nutrition, and avoid products that make unrealistic guaranteed-colour claims. A healthy group with appropriate sexes and space allows natural display. No individual juvenile is guaranteed to become a specific shade.
Rainbowfish are egg scatterers. A conditioned group may deposit adhesive eggs among fine plants or spawning mops. Adults can eat eggs, so breeders usually move the mop or eggs to a separate mature hatching aquarium.
Breeding is an optional specialist project. Do not distribute offspring without accurate species identity, and never release aquarium fish or eggs outdoors.
Eggs are small and adhesive. Move spawning mops gently into water with matching temperature and chemistry, or collect eggs without exposing them to drying. Use gentle flow and inspect for failed eggs without disturbing viable ones unnecessarily.
Newly hatched fry are tiny and need appropriately sized first foods. Infusoria or other microscopic prepared/live foods may be needed before larger Artemia nauplii are accepted. Feed small amounts several times daily while preventing waste accumulation.
| Stage | Priority | Avoid |
|---|---|---|
| Spawning | Clean mop and conditioned adults | Overfeeding the breeder tank |
| Egg incubation | Stable matched water and gentle oxygenation | Large chemistry changes |
| First feeding | Food small enough for the fry | Assuming standard crushed flake is immediately suitable |
| Grow-out | Frequent modest feeds and clean water | Crowding and mixing species identity |
Growth can be uneven. Grade only when necessary and handle fry gently. A grow-out plan must account for the eventual 12 cm adult size and social group needs of every retained fish.
Healthy fish swim strongly, feed promptly, hold fins open and maintain body weight. Warning signs include clamped fins, rapid breathing, white spots, flashing, sores, swelling, hollow profile or isolation from the group.
Test water before medication. Ammonia, nitrite, oxygen shortage, temperature stress and bullying can mimic disease. Correct environmental causes safely and seek an informed diagnosis. Do not combine treatments without evidence that the mixture is appropriate.
Quarantine new fish in a heated, filtered, fully cycled aquarium with a secure lid and matching hard alkaline water. Use separate nets and siphons where possible. Observe feeding, breathing, skin, fins and faeces before joining the main group.
When several fish suddenly gasp, clamp fins, lose balance or crowd the outlet, check ammonia, nitrite, temperature, oxygenation, filter operation and recent chemical exposure immediately. Increase safe aeration and prepare matched dechlorinated water while identifying the cause.
If one fish alone is affected, compare its body condition, fins, breathing and feeding access. An isolation aquarium still needs matching hard water, heat, filtration and a lid.
Stop feeding during a power outage and use battery air if available. Keep filter media wet in aquarium water. Do not rinse it under untreated tap water.
After a prolonged outage, water inside a sealed external filter may be oxygen-depleted and foul. Assess it before sending it back through the aquarium. When power returns, monitor ammonia and nitrite because some biological capacity may have been lost.
Prepare the mature aquarium before delivery. Dim the lights, check temperature and chemistry, and confirm strong oxygenated filter flow. Follow the supplied acclimation instructions and do not pour transport water into the aquarium.
Release the group into open calm water near cover. Offer a modest first meal after settling and confirm every fish eats. Watch for repeated collision, gasping or one fish being excluded.
Use the acclimation timer to organise the process. Review packing, eligible routes and claim requirements on the live-fish delivery page.
Browse the rainbowfish collection to compare adult size, water chemistry and group needs. Red colour alone does not identify this Lake Sentani endemic, and different rainbowfish should not be mixed without enough space for each group.
A group of one species often produces a more coherent display than several pairs of different species. If mixing, avoid hybrids and keep accurate identity records.
For a second Lake Sentani identity, compare the Sentani Rainbowfish. The Spotted Rainbowfish is another Glossolepis species, while the Lake Kurumoi Rainbowfish has a different lake origin and care profile. These links are comparisons, not automatic tank-mate recommendations.
This fish suits a keeper with a mature 120 cm / 250 L+ aquarium, hard alkaline water, strong filtration and room for six or more active adults. It is a poor choice for a small community, soft acidic setup, slow long-finned companions or an owner seeking one red centrepiece fish.
Before ordering, confirm the full group, actual filled volume, swimming length, source-water chemistry, filter capacity and quarantine plan. All current variants will grow beyond their dispatch size.
| Claim | Better guidance |
|---|---|
| “One red rainbowfish makes a centrepiece” | This is a social species that needs a proper group |
| “Every juvenile turns bright red” | Mature males show the strongest red; sex and condition matter |
| “A 100 cm tank is always enough” | FishBase gives 100 cm minimum length; a 120 cm / 250 L+ plan better supports six adults |
| “Peaceful means suitable with any community fish” | Fast activity and feeding can stress slow or timid companions |
| “Hot natural water means the aquarium must stay at 30 C” | A practical 24-28 C range provides oxygen and safety margin |
| “Several rainbowfish species will remain pure” | Hybridisation is possible and identity must be managed |
During week one, focus on breathing, schooling and equal feeding. Test ammonia and nitrite daily after the new bioload enters. Keep lighting moderate and avoid changing decor while the group learns the tank.
During weeks two and three, compare body condition and watch whether sex-related chasing is distributed or focused. Adjust feeding points and planted barriers without reducing the central lane.
By week four, review nitrate trend, filter flow, colour development and group spread. Photograph the whole shoal and representative individuals. Slow weight loss or one fish remaining isolated is a reason to intervene, not simply wait longer.
FishBase reports 12 cm standard length, excluding the tail fin. Adults are also deep-bodied and need substantial swimming room.
Keep at least six. FishBase notes groups of five or more, and six is the practical minimum used here.
Use a 120 cm aquarium of roughly 250 litres or more, with open swimming lanes and strong mature filtration.
A practical captive target is 24-28 C. FishBase records 29-30 C natural water, but high heat leaves less oxygen margin.
No. Mature males develop the strongest red; females and juveniles are usually less red. Sex, maturity and condition affect colour.
No. This is a social shoaling species and should be maintained in a proper group.
Use quality complete pellets or flakes with varied frozen or trusted live daphnia, cyclops, brine shrimp, mysis and insect larvae.
Generally yes, but they are fast and competitive. Slow, timid or long-finned fish can be stressed or outcompeted.
It may be female, juvenile, stressed or socially subordinate. Stable care and maturity help, but colour cannot be guaranteed.
FishBase carries an Endangered IUCN assessment for the wild Lake Sentani species. This listing does not claim the fish is wild caught.
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