Black Samurai Male Betta (Betta splendens)

Recognise the fish and plan for its behaviour

The Black Samurai Male Betta is an ornamental form of Betta splendens, the Siamese fighting fish: a member of the gourami family Osphronemidae from the Mekong basin that reaches 6.5 cm. It suits a careful keeper who can prepare a mature, heated aquarium and house one territorial male alone. The NCBI taxonomy entry records Betta splendens Regan, 1910, while FishBase places the species in Osphronemidae. “Black Samurai” describes the ornamental appearance rather than a separate species.

The representative gallery view shows a black fish with metallic white, armour-like scales and broad black fins. Domestic colour and fin forms can vary substantially: research into domestic Betta diversity documents complex variation in colour, body and fin traits. Use the colour name to choose the look you prefer, but make the husbandry decision from the fish’s identity, adult dimensions and individual swimming ability.

Understand the natural behaviour

FishBase describes wild Betta splendens in standing or sluggish waters including floodplains, canals, rice paddies and rivers in the Mekong basin. It records feeding on zooplankton, mosquito larvae and other insect larvae. The fish is a facultative air-breather with a labyrinth organ, so it regularly needs unobstructed access to the surface; that ability does not replace filtration or clean water.

A male is territorial towards his own kind. FishBase states that males fight, and aquarium guidance recommends keeping the sexes separately except during deliberately managed breeding. For an everyday home aquarium, plan around one male living alone rather than expecting social company to improve his welfare.

Decide whether this Betta suits you

Choose the offer and plan around adult measurements

One purchase supplies one animal. Sex is guaranteed only when the exact product or selected option explicitly states male or female. This Black Samurai Male Betta listing is sold as male.

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.

Dispatch size describes the fish sent, not its final dimensions. FishBase records a maximum length of 6.5 cm total length for male or unsexed Betta splendens. The Seriously Fish species profile uses 70 mm standard length as an aquarium-planning figure. Plan around the FishBase maximum of 6.5 cm and allow clear swimming room for the male’s extended fins.

Use the decisive planning figures

OATA’s broad Betta guidance gives at least 20 litres for one male, 20–28°C, pH 6.0–8.0 and 4–12 dGH. Seriously Fish gives 22–30°C, pH 6.0–8.0 and 1–15 dGH for the species. Tropical Fish Co therefore uses a stable 26–28°C routine target for a typical domestic Betta splendens, keeping aquarium values within the species range while using the narrower UK hardness guidance.

Read the complete Betta care guide before choosing equipment. When you want to compare identities and forms, use the current Betta collection and check each animal’s own page rather than transferring this male’s care or temperament to every member of the genus.

Build a furnished home instead of a bare container

Start with an aquarium of at least 20 litres for one male and choose more capacity where space permits. The litre figure is a starting screen, not the whole decision: substrate and decor reduce usable water, while a wider footprint creates more swimming and furnishing room. Seriously Fish recommends a 45 × 30 cm base or an equivalent aquarium of about 41 litres as large enough for a single male or pair, making that footprint a useful conservative choice for one ornamental male.

Fit the essential equipment

• Mature biological filter: it must process ammonia and nitrite while producing a gentle current.
• Thermostatic heater: select it for the aquarium volume, installation depth and room conditions according to the manufacturer’s instructions.
• Separate thermometer: use it to confirm the water itself stays at 26–28°C rather than relying only on the heater dial.
• Secure cover: leave an air space beneath it and keep the water surface accessible.
• Testing equipment: measure ammonia, nitrite, nitrate, pH and hardness as part of setup and routine maintenance.

Furnish for shade, cover and safe movement

Seriously Fish describes a well-planted, shady aquarium with surface cover, driftwood and shelters. Tall stems, floating plants and other smooth aquarium-safe structures can break up exposed sight lines and provide resting areas. Keep part of the surface clear so the fish can breathe atmospheric air without pushing through a solid plant mat.

Run fingers around ornaments and openings before use. Remove sharp edges, rough textures and holes that could trap the body or catch extended fins. Position shelters so the fish can enter, turn and leave freely. Broad fins may make one individual less able to resist current, so observe movement after every change rather than assuming a filter setting is gentle because its label says so.

A furnished aquarium still needs open swimming room and maintenance access. Avoid packing every area with decor or creating dead spots where waste collects. A practical layout has a clear feeding area, shaded resting cover, an unobstructed route to the surface and enough access for a siphon to remove debris.

Check the finished layout

Mature the biological filter before the fish arrives

Clear water is not proof that an aquarium is biologically ready. Fish release ammonia, which is toxic. A mature biological filter supports bacteria that convert ammonia to nitrite and then to the safer nitrate stage. The RSPCA’s aquarium filtration guidance explains why every fish aquarium needs a correctly established and maintained filter.

Prepare the aquarium before choosing an arrival date. Follow the first tropical aquarium setup and maturation guide, provide the filter with an appropriate ammonia source, test through the cycle and record the results. Add the Betta only after ammonia and nitrite have risen and returned to 0 mg/l and the heated aquarium is holding its intended conditions.

Use a simple readiness gate

1. Fill the aquarium with conditioned water and run the filter and heater continuously.
2. Mature the filter using the fishless process in the setup guide.
3. Measure ammonia and nitrite rather than judging readiness from water clarity or elapsed days.
4. Confirm both readings are 0 mg/l before the planned introduction.
5. Check pH, hardness and temperature so the initial conditions are known.
6. Recheck after the aquarium has run with all decor and equipment in their final positions.

Do not switch off the biological filter as a routine way to calm the current. Instead, adjust the outlet, add a suitable diffuser or choose a gentler filter. Beneficial bacteria depend on continuous water movement and oxygenation, while the fish depends on their waste-processing role.

Protect the filter bacteria

Inspect the filter for reduced flow or blockages during maintenance. When media needs cleaning, rinse it lightly in aquarium water removed during a water change. Do not run it under the tap because chlorine or chloramine may kill the beneficial bacterial population established in the media.

A new fish increases waste and feeding demand. Test more frequently after introduction so a developing ammonia or nitrite problem is found early. If either reading rises above 0 mg/l, treat it as a water-quality problem requiring prompt corrective husbandry: check the filter, remove uneaten food, use conditioned replacement water and continue testing until both readings return to zero.

Hold stable water inside the working range

Use 26–28°C as the routine target for this domestic Betta splendens. Keep pH within 6.0–8.0 and general hardness within 4–12 dGH. These figures are boundaries for steady husbandry, not a reason to chase a preferred decimal or move the fish quickly from one end of a range to the other.

Measure the aquarium itself

Test temperature with a separate thermometer and use suitable tests for pH, general hardness, ammonia, nitrite and nitrate. UK tap-water chemistry varies, and household treatment equipment can change it further. The aquarium water-chemistry guide explains what the readings mean, while the water matcher helps compare measured aquarium values with the working ranges.

OATA advises that nitrate should not exceed 20 mg/l above the normal tap-water level. Compare the aquarium with conditioned source water rather than treating one copied number as meaningful everywhere. A rising trend can reveal excess feeding, accumulated waste, inadequate water changes or a stocking load the system is struggling to process.

Change values gradually

If pH or hardness is within the stated range and remains steady, stability is usually the immediate priority. Do not make large chemical corrections simply to reach the middle. Sudden changes alter more than the number on the test: they change the conditions experienced by the fish and biological filter.

Treat new tap water with an aquarium conditioner that handles the disinfectant used by your water company. Bring replacement water close to the aquarium temperature before adding it, and avoid exposing the fish to an abrupt thermal swing. Record readings and maintenance dates so a change can be traced to a water change, equipment adjustment or new product rather than guessed from memory.

Protect surface access while keeping the current gentle

Betta splendens can breathe atmospheric air through its labyrinth organ, but it still needs a filtered aquarium with good water quality. Keep a clear route to the surface and a small air space under a secure cover. Surface plants can provide shade, provided they do not form a complete barrier.

Judge flow by the fish, not the filter label

Seriously Fish describes the species as coming from sluggish environments and advises avoiding strong water movement. Its worked example for an aquarium of about 41 litres suggests a filter rated around 80–125 litres per hour. Treat that as a planning reference for that tank size, then judge the installed result from how the fish swims and rests.

An air-powered sponge filter set gently is one supported approach, while an adjustable internal filter can also work when its outlet is diffused. The correct choice is the one that maintains waste processing without pushing the fish continuously around the aquarium.

Use the lid correctly

Fit the cover securely, but do not seal the water surface against a solid barrier. Leave warm air space beneath the lid and check that cables, feeding holes and filter cut-outs do not create escape gaps. Position floating cover away from the main breathing route and remove excess growth during maintenance.

Watch for a change after cleaning or repositioning equipment. A filter can produce a stronger jet after a blockage is cleared, while evaporative top-ups can alter the outlet’s relationship to the water surface. Reassess the fish’s swimming whenever the water level, filter media or outlet direction changes.

Feed a measured complete diet with suitable variety

Wild Betta splendens feed on zooplankton, mosquito larvae and other insect larvae. In the aquarium, use a suitably sized complete Betta pellet or quality aquarium flake as the nutritional base. Seriously Fish notes that captive fish normally accept dried products once recognised as food and recommends regular small live or frozen invertebrate foods for condition and colour.

OATA’s feeding guidance for Bettas is to offer only what the fish can eat within a few minutes, once a day. Suitable variety includes small portions of daphnia or bloodworm. Match every item to the fish’s mouth, and remove uneaten food before it decomposes.

Use this daily feeding routine

1. Measure one modest portion rather than shaking food directly into the aquarium.
2. Offer the complete food first so treats do not displace the nutritional base.
3. Watch the fish eat and note whether food is recognised, taken and swallowed.
4. Stop when the measured portion is consumed within a few minutes.
5. Remove leftovers and record any sudden loss of appetite.

Pellet sizes and energy density differ between brands, so a universal pellet count is unreliable. Follow the food maker’s guidance, then adjust the measured portion according to prompt consumption and body condition. Do not use the size of the fish’s eye as a portion formula.

Add variety without losing control

Overfeeding affects both body condition and water quality. Seriously Fish warns that Bettas appear particularly prone to obesity, while OATA explains that uneaten food breaks down and releases waste. If the abdomen becomes progressively enlarged or food remains after feeding, reduce the measured amount and review body condition, diet and test results rather than adding an arbitrary fasting day.

When several people share care, prepare labelled portions so the fish is not fed repeatedly. For an absence, give a responsible carer pre-measured feeds and written instructions, and test any automatic feeder well before relying on it.

Maintain the aquarium with a repeatable weekly routine

Carry out a 25% partial water change at least once each week, following OATA’s Betta guidance. Use a siphon to remove solid waste from accessible substrate, treat replacement tap water with conditioner and bring it close to the aquarium temperature before adding it.

Follow the same sequence each week

1. Observe the fish before disturbing the aquarium: note breathing, posture, swimming, colour, fins and appetite.
2. Measure temperature, ammonia, nitrite, nitrate and pH; check hardness often enough to recognise changes in the supply or aquarium.
3. Remove approximately 25% of the water while siphoning visible debris.
4. Inspect plants, shelters and the surface route, removing damaged material and excess floating growth.
5. Prepare conditioned replacement water and add it without causing a sudden temperature or chemistry change.
6. Check the filter outlet and heater operation after the water level is restored.
7. Record the test results, work completed and any change in the fish.

Never clean every surface and all filter media aggressively at the same time. The biological filter depends on established bacteria, and a heavily stripped system can lose waste-processing capacity. Rinse only the media that needs attention, using removed aquarium water, and preserve the rest of the established system.

Respond to trends before they become emergencies

Top-ups replace evaporated water but do not remove nitrate or dissolved waste, so they do not replace partial water changes. Likewise, a clear aquarium may still contain toxic compounds that only testing will reveal.

Compare the fish with its own usual pattern. Bettas differ in how they rest and explore, but a persistent change matters. A written maintenance log makes it easier to connect unusual behaviour with a missed water change, altered filter flow, equipment fault or feeding change.

Settle the fish carefully and investigate health changes in order

Prepare the aquarium and testing equipment before the parcel arrives, and make sure someone is present to receive live fish. Follow the current delivery and Live Arrival Guarantee policy for the full receiving process and claim requirements.

Use the store acclimatisation steps

1. Be present to receive the parcel; live fish cannot be left unattended.
2. Start filming before the sealed parcel is opened, keeping the outer box visible.
3. Continue filming in one take as the parcel is opened and the fish is shown inside the sealed bag.
4. Open and inspect the parcel on the day it arrives.
5. Float the bag for 20–30 minutes before releasing the fish.
6. Release the fish without pouring the bag water into the aquarium.

OATA advises watching the new fish closely during introduction. Check temperature, confirm that the filter is running gently and make sure the fish can reach the surface. Note posture and breathing so later changes can be compared with an observed baseline.

Use first-week checkpoints

OATA identifies warning signs including hanging at the surface, prolonged bottom sitting, erratic swimming, marked colour change, altered aggression or hiding, faster or slower gill movement, white spots, fluffy growths, damaged fins, body-condition change and reduced feeding.

Investigate before treating

The MSD Veterinary Manual emphasises aquarium history, water analysis and diagnosis. Start by confirming temperature and testing ammonia, nitrite, nitrate and pH. Review recent maintenance, food, additions and equipment changes, then compare the fish with its normal pattern.

Do not combine medicines or raise temperature because one photograph or symptom label looks familiar. A torn fin, white mark, swelling or unusual swimming can have several causes. Correct urgent water-quality faults, preserve a clear history of readings and changes, and use OATA’s fish-vet directory when signs are severe, persistent or unexplained.

Keep one male and treat solitary housing as the default

House this Black Samurai Male Betta as the only male Betta in the aquarium. FishBase states that males fight each other, while OATA warns that two males may continue until one is severely injured or killed. More space, plants or visual barriers do not turn direct male cohabitation into a safe plan.

RSPCA guidance on keeping fish together also recognises that male Bettas may fight their own kind and that compatibility must be researched for the animals involved. Do not divide your attention between two males in one shared water area and assume intervention will always be quick enough.

Avoid these combinations

• Another male Betta: direct cohabitation carries a severe fighting risk.
• Fish with a rival-like body shape or trailing finnage: Seriously Fish says a male may perceive them as rivals.
• Known fin-nipping fish: OATA warns that male Bettas can become targets of intense fin-nipping, leading to stress, disease and death.
• Animals requiring strong current: their flow requirement conflicts with this Betta’s need for sluggish water movement.

Usual practice is also to keep males and females separately unless undertaking deliberately managed breeding. A female is not a routine companion for this offer, and adding one does not create a balanced social group.

Use solitary housing positively

A single-fish aquarium still needs useful structure. Provide plants or smooth refuges, shade, an open feeding area and a direct route to the surface. Place the aquarium so the fish is not forced into continuous visual display at a neighbouring male. If adjacent tanks contain Bettas, block direct sight lines when repeated flaring or agitation occurs.

Solitary does not mean small, bare or unfiltered. The same adult-size, water-quality and furnishing decisions apply: at least 20 litres, a mature biological filter, stable 26–28°C, gentle flow and weekly maintenance. The aim is an environment in which one territorial male can swim, rest, feed and reach the surface without competition.

Screen every proposed tank mate and keep separation ready

Seriously Fish considers Betta splendens unsuitable for a standard community aquarium and says it is best kept alone. An individual may sometimes tolerate other species, but that is the exception rather than the expected result. No named companion is automatically safe for this male.

Pass every compatibility screen first

Seriously Fish names some small cyprinids and loaches from similar environments as possible companions, but only after careful research and with solitary housing still preferred. Treat shrimp, snails and fry as uncertain rather than as guaranteed companions or cleaners. A Betta may investigate or hunt small animals, while larger or defensive invertebrates can introduce different injury risks. Refuges may reduce exposure but do not remove uncertainty.

Know when to separate

Watch for persistent chasing, repeated flaring, hiding, loss of feeding access, torn fins, fin clamping, colour change, rapid breathing or one animal being confined to a small area. Separate promptly when these signs persist; do not wait for visible injury to become severe.

A short calm period does not guarantee long-term compatibility. Behaviour can change after the fish settles, as territories form, during feeding or after furnishings are moved. Continue observing the whole community and keep the backup aquarium mature.

When a proposal fails any screen, keep the Betta alone. If every screen passes, the honest conclusion is still conditional: the combination may work for one individual and fail for another. Solitary housing remains the simplest and most reliable plan.

Answer the key questions before choosing this fish

How big does a Black Samurai Male Betta get?

FishBase records a maximum adult length of 6.5 cm for male or unsexed Betta splendens.

What size aquarium does a Black Samurai Male Betta need?

Use at least 20 litres for one male under OATA’s Betta guidance, with a mature filter, heater, secure cover, gentle flow, plants or smooth refuges and clear surface access.

How many male Betta splendens can I keep together?

Keep one male Betta splendens per aquarium because males may fight until one is severely injured or killed.

Is a Black Samurai Male Betta suitable for beginners?

A careful beginner can keep this fish, but Tropical Fish Co rates its care as intermediate because the heated aquarium must be matured, tested, gently filtered and maintained before the fish arrives.

What does a Black Samurai Male Betta eat?

Feed a measured complete Betta pellet or quality aquarium flake once daily, offering only what it can eat within a few minutes, with suitably sized daphnia or bloodworm as live or frozen variety.

What temperature and pH does Betta splendens need?

Keep Betta splendens at Tropical Fish Co’s stable 26–28°C routine target; pH 6.0–8.0 and hardness 4–12 dGH are the OATA and Seriously Fish overlaps, with ammonia and nitrite at 0 mg/l.

Is a Black Samurai Male Betta aggressive or likely to have its fins nipped?

This male is territorial towards other male Bettas, and OATA warns that known fin-nipping fish can target a male’s fins and cause stress, disease and death.

Which animals can this fish live with?

Keeping it alone is safest. Seriously Fish names some small cyprinids and loaches from similar environments as possible exceptions after careful research; avoid another male Betta, known fin-nippers and fish with trailing fins or a rival-like shape, and keep a mature separation aquarium ready.

How does this fish arrive alive in the UK?

Start filming the sealed parcel before opening it and continue in one take until the fish is visible inside the sealed bag. Someone must be present to receive it; inspect it that day, float the bag for 20–30 minutes, then release the fish without pouring the bag water into the aquarium.

Check the principal identity, welfare and husbandry references

• FishBase: Betta splendens — identity, family, recorded environment, maximum length and wild biology.
• Seriously Fish: Betta splendens — aquarium dimensions, water conditions, furnishing, feeding and behaviour.
• OATA: Siamese fighting fish — UK Betta husbandry, feeding, maintenance and compatibility guidance.
• RSPCA: aquarium environment — biological filtration and waste processing.
• NCBI Taxonomy: Betta splendens — scientific-name reference.
• Kwon et al. 2022 — research into domestic Betta colour, fin and body diversity.
• RSPCA: keeping pet fish together — social compatibility and male fighting risk.
• MSD Veterinary Manual: management of aquarium fish — water analysis, history and diagnostic investigation.
• OATA fish-vet directory — route to UK fish-health assistance.