Albino Koi Swordtail (Xiphophorus hellerii)

Recognise the fish and its needs

The Albino Koi Swordtail is an ornamental form of Xiphophorus hellerii, an active livebearing member of the Poeciliidae family from North and Central America. It reaches 14 cm and suits a keeper prepared to provide a long, filtered aquarium, stable alkaline water and carefully screened companions. Its adult needs matter more than its dispatch size.

FishBase identifies Xiphophorus hellerii as the Green swordtail and records its natural distribution from Veracruz in Mexico to north-western Honduras. Feral populations have also been reported outside that range, with adverse ecological effects recorded in several countries. Keep this aquarium fish contained and never release livestock into local waterways.

Selective breeding has produced many ornamental swordtail colours and fin forms. Some ornamental forms have also involved hybridisation with related Xiphophorus species, but the care plan here follows the identified species, Xiphophorus hellerii. Albino Koi Swordtail is the trade name for this form rather than a separate species.

Choose it for the right aquarium

• Plan around an adult length of 14 cm, not the selected dispatch size.
• Provide an aquarium base of at least 120 × 30 cm or an equivalent footprint.
• Use a filtered aquarium with open swimming room and areas of plant or ornamental cover.
• Screen every companion for matching water needs, adult size and temperament.

You can compare the wider range in our livebearers collection, but assess each fish on its own adult requirements.

Choose the dispatch size, not an adult-size label

One purchase supplies one animal in the size chosen from the live selector. The size choices are 3–4 cm and 4–5 cm. The size you select is the size supplied, not the adult size.

A smaller dispatch size does not indicate a different species, guaranteed sex or permanent adult size. Both sizes require the same long-term aquarium plan, including the adult footprint, water range and social assessment described below.

Plan sex and group structure separately

Sex is guaranteed only when the selected option explicitly states male or female. This Albino Koi Swordtail listing has no sex-guaranteed option.

That distinction matters because OATA’s swordtail guidance recommends a female-biased group when known sexes are deliberately combined. An order of several fish without guaranteed sexes cannot promise that ratio, so base the purchase quantity on the aquarium’s capacity and assess the resulting group composition as the fish develop.

Understand what the gallery represents

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.

Before arranging receipt, read our current delivery and Live Arrival Guarantee policy for the receiving, acclimatisation and claim steps.

Plan the aquarium around the adult measurements

Seriously Fish gives aquarium guidance for Xiphophorus hellerii: a standard length of 140 mm, an aquarium base of 120 × 30 cm or equivalent as the smallest considered, and a volume of about 108 litres. FishBase records a maximum of 14 cm total length. Seriously Fish also records 14 cm standard length.

Keep routine water at 22–27°C, pH 7.0–8.0 and 10–12 dGH. These values are the overlap of FishBase’s recorded environmental range, the Seriously Fish aquarium range and OATA’s platy and swordtail group guidance, giving one practical range that sits within all three.

Treat the footprint as the first space test. A taller aquarium can contain the same volume while offering less horizontal swimming room, so litres alone do not replace the 120 cm length and 30 cm front-to-back base. Once that requirement is met, assess the final group and all other residents before deciding how many fish the aquarium can support.

The water figures are operating ranges rather than a single target point. Choose stable conditions within all three ranges and suitable for every resident; a temperature match alone is not enough when pH or hardness falls outside the overlap.

Build open swimming space without removing cover

Start with a base of at least 120 × 30 cm or an equivalent horizontal footprint. About 108 litres is the associated planning volume, but the final capacity depends on the complete group, the adult sizes of other residents and the space occupied by décor. More fish require more usable room rather than simply more decoration.

Divide the footprint deliberately

Keep a clear route through the aquarium for swimming, then use plants, roots, branches or suitable ornaments to create sheltered areas. Seriously Fish notes that the choice of décor is not especially critical and that the species tends to look particularly effective in a heavily planted aquarium with a dark substrate. Floating plants and driftwood roots or branches may diffuse incoming light and add a more natural feel.

Live plants are useful cover, but they are not compulsory. OATA’s platy and swordtail guidance recommends aquarium gravel or sand and ideally live plants; where live plants are not used, plastic plants and suitable ornaments such as model caves or plant pots can provide shelter. Check that every item is intended for aquarium use and arrange it so the adult fish still has open space.

Use movement without overpowering the aquarium

Filtration does not need to be particularly strong, although a degree of water movement appears to be appreciated. Position the return so water circulates through the aquarium while preserving usable swimming space and shelter. The filter must still meet the required biological and mechanical workload; flow appearance alone does not show whether waste is being processed.

A stream-style arrangement with water-worn rocks and small boulders is mentioned for wild forms. For this ornamental fish, prioritise the verified footprint, cover and open swimming route rather than trying to copy a wild display at the expense of practical care.

Match temperature, pH and hardness together

Keep this fish at 22–27°C, pH 7.0–8.0 and 10–12 dGH. This routine range is the overlap of FishBase, Seriously Fish and OATA values. Measure all three before introduction and continue checking them as part of routine maintenance. Our water chemistry guide explains what the main measurements mean, while the water matcher helps compare your readings with these ranges.

Read the values as a combined test

A single matching value is therefore not enough. If any reading falls outside the range, resolve that mismatch before adding the fish rather than assuming the other values compensate for it. Apply the same test to every proposed companion so the aquarium can be run within a genuine overlap.

Control dissolved waste as well as mineral values

OATA’s platy and swordtail sheet gives group guidance: ammonia should be zero mg per litre, nitrite should be zero mg per litre, and nitrate should not exceed 20 mg per litre above the normal level in the tap water. These waste targets do a different job from pH and hardness; suitable mineral chemistry does not make ammonia or nitrite acceptable.

Test at least weekly and whenever behaviour, breathing, colour, condition or feeding changes. Compare nitrate with the conditioned tap-water baseline rather than treating the aquarium result in isolation. A larger aquarium generally offers more stable temperature and water conditions, but it still requires filtration, testing and water changes.

Mature the filter before introducing the fish

A working biological filter is essential. The RSPCA explains that fish release toxic ammonia; beneficial bacteria in a properly established filter convert it first to nitrite, which is also toxic, and then to the safer nitrate. The aquarium should therefore be filtered and matured before livestock is introduced.

If this is your first aquarium, prepare it with our first tropical tank guide. Confirm ammonia and nitrite are both zero mg per litre before adding the fish. Increase the population slowly because the bacterial population must respond when fish numbers and feeding increase.

Size circulation for the example aquarium

For an aquarium of about 108 litres, Seriously Fish gives a turnover of four to five times the aquarium volume per hour and a filter rating of roughly 430–540 litres per hour.

Use those figures as a rating guide for the example volume. Filter condition, blockages and the way flow moves around hardscape still need routine checks. A visibly moving surface does not replace ammonia and nitrite testing.

Prepare heat before livestock arrives

Seriously Fish gives a rough heater guide of 75–125 W for an aquarium of about 108 litres when the room is around 20°C. Set up and monitor the equipment before introduction so the aquarium is already holding a stable point within the routine 22–27°C range. Match that operating point to the needs of all residents.

Introduce livestock in controlled stages

1. Confirm the aquarium footprint and final stocking plan.
2. Measure temperature, pH and general hardness.
3. Check ammonia and nitrite are both zero mg per litre.
4. Ensure the filter is operating without blockage.
5. Add livestock slowly rather than making a large population increase at once.
6. Continue testing as feeding and biological load increase.

Maintain the aquarium every week

Carry out a 25% partial water change at least once every week. Use a siphon to remove solid waste from the substrate, and treat replacement tap water with a suitable conditioner before it enters the aquarium so chlorine or chloramine does not harm the fish or filter bacteria.

Combine the change with measured checks

Testing and water changing answer different questions. A clear-looking aquarium can still contain dissolved waste, while a test result does not remove debris from the substrate. Complete both parts of the routine and record results so a change from the aquarium’s usual pattern is easier to recognise.

Protect the biological filter

When filter media needs cleaning, rinse it lightly in aquarium water removed during the partial change. Do not run it under the tap because chlorine or chloramine may kill beneficial bacteria and reduce the filter’s ability to process ammonia and nitrite.

Clean only when needed to restore flow or remove accumulated debris. Check the filter for blockages every week rather than waiting for circulation to stop. After any filter work, confirm that the unit has restarted and that water is moving through the media.

Use a first-month checkpoint

• During each of the first four weeks, test ammonia, nitrite and nitrate at least once.
• Compare the latest readings with the previous result and with the conditioned tap-water baseline.
• If ammonia or nitrite rises above zero, treat the result as a water-quality problem and reassess recent stocking, feeding and filter operation.
• If nitrate approaches the permitted rise above tap water, complete the scheduled partial change and review waste production.
• Keep the weekly routine after the first month; a mature filter still requires maintenance.

Feed one controlled meal each day

Albino Koi Swordtails are omnivorous. Stomach analyses of wild Xiphophorus hellerii found aquatic and terrestrial invertebrates, organic detritus, algae and other plant material. In the aquarium, use a varied diet rather than relying on one food.

Build the meal around a reliable staple

Offer a good-quality flake or granule with a high algae content. Small live or frozen items such as daphnia, bloodworm or tubifex can supplement the staple, while Seriously Fish also lists Artemia and chironomid larvae among suitable small foods. A good-quality dried product should remain part of the balanced diet.

Feed only what the fish can consume within a few minutes, once a day. That is one controlled feeding period, not a succession of separate meals for every food type in the table. Rotate suitable foods within the balanced plan while keeping the total portion inside the same few-minute limit.

Let leftovers guide the next portion

If food remains after the feeding period, the portion exceeded the stated limit. Reduce the next day’s amount instead of assuming an active fish needs more. Excess food breaks down and releases waste, increasing pressure on the filter and contributing to unhealthy water conditions.

Watch every fish during the meal. Reduced intake or a loss of interest in food is one of OATA’s warning signs, especially when it appears alongside altered swimming, breathing, colour or condition. Test the water if feeding behaviour changes rather than treating appetite as a stand-alone issue.

Adjust the food, not the feeding frequency

Choose pieces small enough for the fish to take readily. When using frozen or live items, count them as part of the day’s portion rather than adding them after a full dried-food meal. This keeps variety in the diet without turning variety into overfeeding.

Plan a social group without assuming its sex ratio

OATA recommends companionship for platies and swordtails and suggests keeping at least three. Its preferred composition is two females for each male, intended to reduce stress on females and other aquarium residents. Larger groups can be considered when the aquarium has enough additional volume and usable space.

Separate group quantity from sex selection

One purchase supplies one animal, so a planned group of three requires three fish. Quantity alone does not create the recommended sex ratio: this offer does not guarantee male or female. Do not interpret dispatch size, colour or the representative gallery as a sex indicator.

Seriously Fish reports that groups of males in confined spaces tend to form dominance hierarchies and may spend a significant amount of time maintaining their positions. That makes footprint and group composition practical welfare issues, not merely display preferences. If repeated competition appears, reassess crowding, the number of males and the shelter layout.

Allow for livebearing biology

Xiphophorus hellerii is a livebearer. Male Xiphophorus use a modified anal fin for internal fertilisation, and females can store viable sperm for months. A female may therefore produce live young after separation from a male. Include potential population growth in the long-term space and filtration plan rather than treating the initial headcount as permanently fixed.

A small group needs the full adult aquarium plan from the beginning. Do not use the current juvenile body size to fit three fish into a temporary footprint that will become unsuitable as they grow. If the aquarium already contains other livestock, count those residents when assessing volume, swimming room and biological load.

Respond to health changes with water tests first

Learn the usual appearance and behaviour of each fish so changes stand out. Individual fish vary, making a change from the normal pattern more useful than one isolated posture without context.

Watch behaviour and breathing

• Check for hanging at the surface, sitting on the bottom or erratic swimming.
• Notice increased hiding or a change in aggression.
• Compare the speed of gill-cover movement with the fish’s usual breathing.
• Confirm the fish still approaches and consumes its daily food.

Check the body and fins

• Look for a darker or paler appearance than normal.
• Check for white spots, fluffy growths, bumps or ulcerated areas.
• Inspect the fins and scales for loss or damage.
• Watch for an increase or decrease in body weight and overall condition.

When any of these changes appears, test ammonia, nitrite, nitrate, temperature, pH and hardness. Ammonia and nitrite should remain at zero mg per litre, while nitrate should remain within 20 mg per litre of the normal tap-water level. Compare temperature, pH and hardness with the routine overlap of 22–27°C, 7.0–8.0 and 10–12 dGH.

Do not choose a response from one sign alone. A breathing change, for example, must be considered alongside water-test results, filter performance, temperature and the behaviour of other residents. Record when the change began and whether it affects one fish or several.

If you are concerned about a health change, contact us after testing the water so the readings and observed signs can guide the next step.

Screen every companion before combining fish

OATA describes platies and swordtails as generally peaceful and compatible with other species, but it also warns that large swordtails can be boisterous and may chase more timid tankmates. Seriously Fish adds that males in confined spaces can form dominance hierarchies. Compatibility therefore depends on the exact aquarium and residents rather than a universal list of named companions.

Apply five checks in order

1. Water: confirm a shared operating range within 22–27°C, pH 7.0–8.0 and 10–12 dGH.
2. Adult size: use the swordtail’s recorded maximum of 14 cm total length and the adult size of every companion.
3. Footprint: start with at least 120 × 30 cm or an equivalent base, then allow more capacity for the complete community.
4. Temperament: treat timid fish cautiously because a large, active swordtail may chase them.
5. Group structure: account for the swordtail group, possible male competition and all existing livestock.

Passing one check never cancels failure elsewhere. A peaceful fish that needs acidic, softer water is not matched simply because its temperament appears suitable. Likewise, shared chemistry does not make a cramped footprint acceptable.

Observe the whole community after any introduction. Changes in hiding, aggression, feeding, fin condition or swimming can reveal a poor interaction before serious damage develops. If you want a stocking assessment, contact us with the aquarium dimensions, measured water values, filter details and the adult identity and quantity of every resident.

Work through the stocking decision with measured examples

Begin with the actual base dimensions and water-test results, not the aquarium’s marketing label. Then list every resident at its adult size and note whether any fish is timid or likely to compete for the same open swimming area.

Compare common planning situations

Count the adult community

The approximately 108-litre figure is the species reference attached to a 120 × 30 cm base, not a promise that every proposed community will fit. A group of swordtails plus other adult fish places a greater demand on swimming room and filtration than one juvenile fish. OATA also advises that more fish require a larger volume.

For example, adding one fish to an established swordtail group is not automatically simpler than starting a new group. Check the existing sex balance, adult headcount, behaviour and water values first. The one-fish purchase unit describes the transaction; it does not answer whether that additional animal suits the aquarium.

Make behaviour part of the final decision

General peacefulness is a starting description rather than an assurance for every pairing. Give special attention to timid residents and to male swordtails sharing confined space. After introduction, compare hiding, chasing, feeding and fin condition with the normal pattern for each fish.

If all measured ranges overlap, the aquarium meets the minimum footprint and the final adult community has adequate space, the combination passes the initial screen. Continue monitoring because social behaviour can still change as fish grow or group composition changes.

Answer the essential buying and care questions

How big does an Albino Koi Swordtail get?

FishBase records the Albino Koi Swordtail species at a maximum of 14 cm total length. Plan its aquarium around that adult figure rather than the fish’s dispatch size.

What size aquarium does Xiphophorus hellerii need?

Seriously Fish says an aquarium with a base of at least 120 × 30 cm or equivalent should be the smallest considered, with an associated volume of about 108 litres. Preserve open swimming room and provide plant or ornamental cover.

How many swordtails should I keep together?

OATA suggests keeping at least three swordtails and using two females for each male when known sexes can be chosen. This fish is sold without guaranteed sex, so plan enough adult space and assess the resulting group composition.

Is the Albino Koi Swordtail suitable for beginners?

OATA describes most swordtails as undemanding and easy to keep, but this fish still needs a mature filtered aquarium, at least a 120 × 30 cm base, stable water and a planned social group.

What does this fish eat?

Feed good-quality flake or granules with a high algae content, supplemented with small live or frozen foods such as daphnia, Artemia, bloodworm or tubifex. Offer once a day only what it can eat within a few minutes.

What temperature and pH does the Albino Koi Swordtail need?

Keep the Albino Koi Swordtail at 22–27°C, pH 7.0–8.0 and 10–12 dGH, the overlap of FishBase, Seriously Fish and OATA ranges. Ammonia and nitrite should remain at zero mg per litre.

Is this fish aggressive or likely to nip fins?

OATA describes swordtails as generally peaceful, but large swordtails may be boisterous and chase timid tankmates. Seriously Fish reports that males in confined spaces may form dominance hierarchies, so provide adequate room and monitor chasing, hiding and fin condition.

Which kinds of animals can an Albino Koi Swordtail live with?

Screen potential companions for a shared range within 22–27°C, pH 7.0–8.0 and 10–12 dGH, compatible adult size, adequate swimming space and suitable temperament. Treat timid fish cautiously because large swordtails may chase them.

How does the Albino Koi Swordtail arrive alive in the UK?

Start filming the sealed parcel before opening it and continue in one take as it is opened, keeping the fish visible inside the sealed bag. Someone must be present to receive the parcel; inspect it that day, float the bag for 20–30 minutes before releasing the fish, and never pour the bag water into the aquarium.

Check the care reference library

• FishBase: species identity, family, distribution, recorded environment and maximum total length.
• Seriously Fish: aquarium footprint, approximate volume, water range, filtration, décor, diet, behaviour and reproductive biology.
• Ornamental Aquatic Trade Association: platy and swordtail guidance on groups, feeding, water quality, maintenance, introduction and health observations.
• RSPCA: general aquarium filtration and biological waste-processing guidance.
• Tropical Fish Co delivery policy: receiving, acclimatisation and Live Arrival Guarantee steps.