Peaceful Betta / Crescent Betta (Betta imbellis)

Meet this small wild-type labyrinth fish

The Peaceful Betta, also called the Crescent Betta, is Betta imbellis, a freshwater member of the gourami family Osphronemidae. It is a wild-type betta rather than one of the many ornamental forms of Betta splendens. It suits a keeper who can provide shade, planting, shelter, gentle water movement and calm solitary housing. Its common name is useful identification, but it should never be read as a promise that every individual will accept another betta or a busy community.

FishBase records Betta imbellis from Thailand, Malaysia, Singapore and Indonesia, with a maximum recorded length of 6 cm standard length. Use that 6 cm SL figure for adult planning.

A labyrinth organ allows atmospheric air breathing, but filtration and good water quality remain essential. Keep unobstructed routes to the surface alongside floating or reaching plants so the fish can breathe, feed and rest without pushing through a solid layer of foliage.

Browse the current betta collection if you are comparing wild-type and ornamental bettas before deciding.

Plan around adult needs, not the dispatch size

One purchase supplies one animal, with a dispatch size of 1.5–3 cm. This measurement describes the fish prepared for dispatch; it is not an adult-size estimate and does not change the 6 cm SL planning reference.

A small dispatch fish still needs an aquarium arranged for its eventual size, behaviour and feeding access. Do not begin with temporary, minimally decorated housing simply because the fish arrives small. Prepare the planted footprint, gentle filtration and sheltered surface areas before introduction, then allow the fish to use that complete environment as it grows.

Read the offer in the right order

1. Confirm the unit: one purchase means one fish, not a pair or group.
2. Separate dispatch and adult figures: 1.5–3 cm is the dispatch size; up to 6 cm SL is the adult planning reference.
3. Assess the aquarium: base dimensions, planting and water movement matter alongside volume.

Sex is guaranteed only when the selected option explicitly states male or female. This Peaceful Betta / Crescent Betta listing has no sex-guaranteed option.

Keep sex assumptions separate from colour, fin shape, body size and gallery appearance. Those visual features do not alter the offer.

The gallery images are representative, based on reference photographs of this species, so colours can look slightly different from the live animal.

For dispatch arrangements and guarantee terms, read our delivery and Live Arrival Guarantee policy before ordering.

Check the decisive space and water numbers

Keep the aquarium at 24–28°C, pH 6.0–7.0 and 5–10 dGH. These routine values are the overlap of FishBase's recorded environment range and Seriously Fish aquarium guidance for Betta imbellis. Seriously Fish describes a 45 × 30 cm base, approximately 41 litres, as large enough for a pair.

Treat the footprint and volume together: a tall container with the same litres does not automatically provide the same horizontal layout. The pair figure is not permission to place any two fish together without observation. Behaviour, cover and the ability of each fish to feed and retreat still decide whether shared housing works.

Solitary keeping remains the simpler plan, particularly when sex and individual temperament are unknown. Choose this fish when your measured water can remain within the routine overlap without abrupt adjustments and when the aquarium can carry substantial planting without losing surface access.

Build shade, cover and clear surface access

Arrange a well-planted, shady aquarium with several distinct sheltered areas. Tall stem plants, floating plants such as Salvinia or Riccia, tropical lilies from the genus Nymphaea and rooted Cryptocoryne can all contribute cover. The aim is not to fill every centimetre: combine shade with open routes to the surface because a betta must be able to reach atmospheric air without forcing through a solid raft of foliage.

Layer the aquarium from bottom to surface

• Lower level: use wood, plants and sheltered gaps to create retreats away from direct view.
• Middle level: place stems and broad plant groups so one fish cannot oversee the entire aquarium from a single position.
• Surface level: add floating or reaching plants in patches while retaining clear breathing and feeding spaces.
• Quiet shelters: small clay plant pots or suitable lengths of inert plastic piping can provide additional cover.

Driftwood gives structure and can carry plants such as Microsorum or Taxiphyllum. Position each piece securely and leave enough open room for normal swimming. A useful layout has more than one route around the wood, preventing a dominant fish or tank mate from controlling the only path between shelter and the surface.

Dried leaf litter can provide extra cover. As it decomposes, microbial colonies may develop and can become a secondary food source for fry. Tannins and other substances released by decaying leaves are also considered beneficial in this style of aquarium. Introduce botanicals deliberately and include them in the regular maintenance check rather than allowing waste and decomposing material to accumulate without observation.

Test the layout before introduction

Trace at least two routes from the lower shelters to an open surface patch. Then view the aquarium from the front and both ends. Plants or wood should interrupt long sight lines while leaving room for ordinary swimming. This check matters most when two fish are being considered because each needs a way to leave an interaction without entering another exposed area.

Review the finished layout from several angles. If every shelter remains visible from every other shelter, add or reposition plants. If floating growth blocks nearly all surface access, thin it. The successful balance is shaded and structured, not sealed or cramped.

Match filtration and heating to gentle water movement

This betta naturally uses sluggish environments, so strong water movement should be avoided. For an aquarium around 41 litres, the species guidance points to a filter rated approximately 80–125 litres per hour. That rating is a practical starting point rather than a reason to direct the full outlet at the fish. Position or diffuse the return so plants move gently and the fish can hold position without constant effort.

An air-powered sponge filter is a useful way to combine biological filtration with subdued flow. A gently adjusted internal filter can also work when its return does not dominate the aquarium. Watch the fish and floating plants after installation: persistent displacement across the tank, continual sheltering directly behind hardscape or difficulty remaining at the surface all call for a gentler outlet arrangement.

The RSPCA explains why a working biological filter is vital: fish release toxic ammonia, and established beneficial bacteria convert it first to toxic nitrite and then to safer nitrate. Atmospheric air breathing does not remove the need for this process. A labyrinth organ is an additional breathing adaptation, not a substitute for a maintained filter.

Prepare the equipment before the fish

1. Set up and establish the biological filter before introducing livestock.
2. Confirm that the outlet produces gentle circulation throughout the planted layout.
3. Use a heater and thermometer to hold a stable value within 24–28°C.
4. Check that plants and shelters do not prevent maintenance access or surface breathing.

At about 41 litres, the species profile suggests roughly 50 W of heating when the room is around 20°C. Room temperature, aquarium position and equipment design affect heater operation, so use the thermometer to confirm the result. Our first tropical aquarium guide can help you prepare and mature the system before livestock arrives.

Use behaviour to refine the flow

Check several positions rather than judging only the filter outlet. A suitable arrangement lets the fish move between cover, feeding space and the surface without being swept aside. If floating plants are driven continuously to one end or the fish can rest only behind one object, redirect or diffuse the return. Preserve biological filtration while changing how the water enters the aquarium.

Measure the water before making adjustments

Keep the aquarium between 24 and 28°C, with pH from 6.0 to 7.0 and hardness from 5 to 10 dGH. These routine values are the overlap of FishBase's recorded environment and Seriously Fish aquarium ranges. Choose a stable point within each range that your source water and aquarium can maintain; repeated abrupt changes made to chase a particular number are not a sound substitute for regular measurement.

OATA's broad betta guidance sets ammonia at 0 mg/l, nitrite at 0 mg/l and nitrate at no more than 20 mg/l above the normal level in the tap water. Use these waste limits as routine safety targets for a filtered betta aquarium.

Test the aquarium and the tap water rather than relying on regional assumptions. Our water chemistry guide explains what the principal readings mean, while the water matcher lets you compare measured aquarium values with the stated range.

Interpret the readings as a set

A pH within range does not make an aquarium ready when ammonia or nitrite is detectable. Likewise, suitable temperature does not compensate for hardness outside 5–10 dGH. Work through every value before introduction and distinguish source-water chemistry from waste produced inside the aquarium. Comparing tap and tank nitrate shows how much nitrate has accumulated rather than treating the aquarium reading in isolation.

If a reading sits outside the target, identify the cause before adding fish or making a large correction. Check the test method, replacement water, recent feeding, stocking and filter operation. Controlled changes protect the fish from both the unsuitable value and the stress of a rapid swing.

Feed small portions and protect body condition

In nature, Betta imbellis is likely to prey on aquatic and terrestrial invertebrates. In the aquarium, individuals normally accept dried food once they recognise it as edible, but small live or frozen foods should form a regular part of the routine. Suitable examples include Daphnia, Artemia and chironomid larvae such as bloodworm.

Use a good-quality dried product in a size the fish can take easily, then rotate appropriate live or frozen items to support colour and condition. Watch the first few mouthfuls. Food that is repeatedly mouthed and rejected may be too large or not yet recognised, while food that falls out of reach can decay and add waste to the aquarium.

Use one measured daily feeding routine

1. Offer only what the fish can finish within a few minutes.
2. Check that the betta reaches the food before any companion clears it.
3. Remove uneaten material rather than allowing it to break down.
4. Use regular small live or frozen foods alongside the accepted dried diet.
5. Judge the next portion from body condition and the previous feeding response.

OATA's betta feeding guidance recommends feeding once a day and limiting the portion to what can be eaten within a few minutes. This schedule provides a clear starting point and helps prevent repeated extra feeds prompted by begging behaviour.

Respond to the feeding result

• Food disappears immediately: do not assume the portion was too small; use body condition and the few-minute limit before changing it.
• Dried food is ignored: offer an appropriately small item and allow the fish to recognise it as food rather than leaving rejected pieces to decay.
• A companion takes the meal: reconsider the shared arrangement because the betta must receive its measured portion.
• Appetite changes: check water, breathing, swimming and interactions before increasing food.

Avoid overfeeding. Bettas are described as particularly prone to obesity, and excess food also increases the waste presented to the biological filter. If body condition rises, reduce the portion rather than removing dietary variety. If appetite falls, check water quality, breathing, swimming and interactions before offering a larger or richer meal.

Keep a consistent weekly maintenance routine

Carry out a 25% partial water change at least once a week. Use a siphon to remove visible solid waste from the substrate, and treat replacement tap water with a suitable conditioner to remove chlorine or chloramine before it enters the aquarium. Keep the replacement conditions close enough to the aquarium conditions to avoid abrupt changes.

Complete the same checks each week

• Test: measure ammonia and nitrite at least weekly and compare nitrate with the tap-water baseline.
• Change water: replace 25% at least once a week, removing settled debris as you siphon.
• Inspect flow: check the filter for blockages and confirm that circulation remains gentle.
• Review planting: thin floating growth if it restricts surface access, and remove loose decaying material where it traps waste.
• Observe the fish: compare appetite, body condition, breathing, colour and swimming with its normal pattern.

If filter media needs cleaning, rinse it lightly in aquarium water removed during the water change. Do not run it under the tap because chlorine or chloramine may kill the beneficial bacterial population established in the media. Avoid replacing all mature media at once unless the equipment instructions make a particular component disposable.

Keep the sequence predictable

Test before disturbing the aquarium so the result reflects the water the fish has been living in. Siphon waste during the partial change, treat the replacement water, then check the filter and surface access before finishing. This order links each observation to an action and makes it easier to notice whether waste, blocked flow or excessive floating growth is changing between weeks.

The value of a routine is consistency. Weekly testing can reveal a rising waste trend before the fish displays obvious distress, while a regular water change prevents neglected debris from becoming a larger problem. Record unusual readings and the action taken so you can distinguish a one-off result from a developing pattern.

Increase maintenance attention after any change that increases feeding or livestock load. Beneficial bacteria need time to respond to additional waste, and adding too many fish too quickly can produce new tank syndrome with harmful ammonia or nitrite.

Plan the introduction and first month carefully

Prepare the aquarium before introduction. Confirm that the biological filter is established, temperature sits within 24–28°C, pH is 6.0–7.0, hardness is 5–10 dGH, and both ammonia and nitrite read 0 mg/l. Check that the planted layout contains shelter, gentle circulation and open routes to the surface.

Follow the arrival steps in order

1. Be present to receive the parcel because live fish cannot be left unattended.
2. Start filming with the parcel still sealed and the outer box visible.
3. Open the parcel in one continuous take, keeping the fish visible inside the sealed bag before anything is disturbed.
4. Float the bag for 20–30 minutes before releasing the fish.
5. Never pour the bag water into the aquarium.

Use clear checkpoints

A healthy fish should show clear, bright eyes, intact scales and fins, steady breathing and appropriate swimming behaviour. Every fish has an individual normal pattern, so look for change rather than demanding constant display. A fish using cover is not automatically in difficulty; a sudden increase in hiding combined with poor appetite or altered breathing needs investigation.

Build a useful baseline

During the first week, note where the fish rests, which route it takes to the surface and how promptly it approaches food. These observations create a practical comparison for later checks. A change in one detail may call for closer watching; several changes together, such as altered breathing, reduced feeding and unusual swimming, call for immediate water testing and an environmental review.

Warning signs include hanging at the surface, prolonged sitting on the bottom, erratic swimming, unusual darkening or paling, changed aggression, faster or slower gill movement, white spots, fluffy growths, damaged fins or scales, body-condition change and reduced feeding interest.

If you see a concerning change, test water quality first and review filter operation, recent feeding and tank-mate behaviour. Contact us for further health guidance when the change persists or the test results do not explain it. Choose any treatment only after the problem has been properly assessed.

Choose solitary housing unless the shared plan is strong

Betta imbellis is not recommended for a standard community aquarium. Its needs and disposition make solitary keeping the most dependable starting point, while very peaceful companions may be considered in a carefully planned aquarium. The word “peaceful” is a relative common name, not permission to crowd fish together.

Compare the two practical plans

More than one male may be kept when there is sufficient cover, according to the species profile, but that is a conditional possibility rather than a universal group recommendation. Dense structure must break sight lines and allow a fish to leave an interaction without being followed immediately into the next shelter.

Set failure points before sharing

• Sustained pursuit: separate the fish rather than waiting for visible injury.
• Blocked feeding: act when one fish repeatedly prevents another from reaching its portion.
• Restricted surface access: change the arrangement if a fish cannot reach atmospheric air without crossing a defended area.
• Loss of condition: treat declining body condition as evidence that the social plan is not working.

Watch access to food as closely as chasing. A fish repeatedly displaced from the feeding area, confined to one corner or prevented from reaching the surface is not benefiting from the nominal aquarium volume. Separate fish when sustained pursuit, blocked feeding or loss of condition shows that the arrangement is failing.

Pairs are best isolated for breeding purposes. For ordinary display keeping, do not assemble a pair or group by guessing sex from size, colour, fins or photographs. Build the plan around the actual unit purchased and make any later additions only after a fresh compatibility assessment.

Screen every companion for behaviour and water needs

Some small cyprinids and loaches from similar environments may be suitable, but the category name alone is not enough to approve a particular species. Compare adult size, preferred temperature, pH, hardness, water movement, swimming level, feeding behaviour and social requirements before adding any companion.

OATA's general betta guidance warns that males can become targets of intense fin nipping even when they are not aggressive towards the other species. For Betta imbellis, combine that warning with the species advice favouring solitary housing or only very peaceful companions.

Reject a match at the first failed screen

A candidate that fits the temperature range but needs strong current is not suitable. A calm fish with overlapping pH and hardness still needs review if its social group would overcrowd the aquarium or compete heavily at feeding time. Passing one test never cancels a failure elsewhere; the complete combination must protect access to food, shelter and the surface.

Do not treat shrimp, snails, bottom dwellers or any named community fish as universally safe. The practical rule is the same for every candidate: matching water values are necessary, but calm behaviour, feeding access, sufficient space and the ability to retreat decide whether the combination is workable.

For a stocking and compatibility assessment, contact us with the aquarium's dimensions, measured water values, established livestock and planting plan. Honest compatibility remains conditional because individual fish can behave differently even when the broad screen looks favourable.

Answer the key questions before choosing

How big does the Peaceful Betta / Crescent Betta grow?

FishBase records a maximum adult length of 6 cm SL for Betta imbellis; plan the completed aquarium around that adult figure.

What size aquarium does Betta imbellis need?

Seriously Fish describes a 45 × 30 cm base, approximately 41 litres, as large enough for a pair. Treat the footprint and volume together and provide shade, planting, shelter and gentle flow.

How many Peaceful Bettas can I keep together?

Solitary housing is the simplest plan. Seriously Fish says more than one male may be kept with sufficient cover, while a pair needs at least a 45 × 30 cm base of about 41 litres and close observation.

Is Betta imbellis suitable for beginners?

Choose it only if you can maintain gentle flow, dense cover, open surface access and stable water at 24–28°C, pH 6.0–7.0 and 5–10 dGH. These values are the overlap of FishBase and Seriously Fish ranges.

What does Betta imbellis eat?

Offer a good-quality dried food plus regular small live or frozen Daphnia, Artemia or bloodworm. Feed once daily and only what it finishes within a few minutes.

What temperature and pH does the Peaceful Betta need?

Keep it at 24–28°C, pH 6.0–7.0 and 5–10 dGH, the overlap of FishBase's recorded environment and Seriously Fish aquarium ranges.

Is Betta imbellis aggressive or likely to have its fins nipped?

Solitary housing is preferred because the species is not recommended for a standard community aquarium. Avoid fin-nippers, boisterous fish and aggressive fish, and separate fish if pursuit or blocked feeding persists.

Which animals can this fish live with?

Some small cyprinids and loaches from similar environments may be suitable after screening for calm behaviour, matching water needs, gentle-flow requirements, feeding access and sufficient space. No companion is universally safe.

How does the Peaceful Betta arrive alive in the UK?

Film every delivery continuously from the sealed parcel as you open it, keeping the fish visible inside the sealed bag before anything is disturbed. Be present to receive the parcel, float the bag for 20–30 minutes before release and never pour the bag water into the aquarium.

Reference reading

• FishBase: Betta imbellis — scientific identity, family, distribution, recorded environment and maximum recorded length.
• Seriously Fish: Betta imbellis — aquarium footprint, water, layout, diet and behaviour guidance.
• OATA: Siamese fighting fish and bettas — UK group guidance on water quality, feeding, maintenance, introduction and compatibility.
• RSPCA aquarium environment guidance — biological filtration and waste processing.
• Tropical Fish Co delivery and Live Arrival Guarantee policy — packing, arrival, acclimatisation and claim procedure.