Swordtail Red Wagtail (Xiphophorus helleri red wagteil)

Choose this active livebearer for a planned community

The Swordtail Red Wagtail (Xiphophorus helleri) is an ornamental poeciliid livebearer from a species native to North and Central America, from the Rio Nantla area of Veracruz, Mexico, to north-western Honduras. It reaches 14 cm and suits beginners who can provide a mature, filtered aquarium with enough length for active swimming. FishBase records the species in freshwater and brackish environments and describes adults in rapidly flowing streams and rivers, warm springs, weedy canals and ponds, with a preference for heavily vegetated habitats. FishBase now lists it as Xiphophorus hellerii.

Plan around an aquarium measuring at least 120 × 30 cm at the base, or an equivalent footprint, with a volume of about 108 litres or more. Seriously Fish recommends that footprint as the smallest considered. Keep the routine water at 22–27°C, pH 7.0–8.0 and 10–12 dGH. These values are the overlap of the Seriously Fish aquarium range, the FishBase recorded environment and OATA’s swordtail guidance.

Companionship needs deliberate planning. OATA’s swordtail group guidance suggests keeping at least three, using two females to each male to reduce stress on females and other inhabitants. This is group guidance, not a species-specific minimum. OATA describes most swordtails as peaceful, undemanding and easy to keep, although large specimens can be boisterous and may chase timid tankmates.

Select the dispatch size and plan for growth

One purchase supplies one Swordtail Red Wagtail in the size selected on the live selector. The listed choices are 3–4 cm, 4–5 cm and 5–6 cm. The size you select is the size supplied, not the adult size. Every choice therefore needs the same long-term aquarium plan for a fish that can reach 14 cm.

Sex is guaranteed only when the selected option explicitly states male or female. This Swordtail Red Wagtail listing has no sex-guaranteed option. Build any group gradually and confirm its composition rather than using colour, body size or the sword-like tail as a guarantee of sex. Seriously Fish notes that adult males typically possess a gonopodium and the characteristic lower caudal-fin extension, but ornamental strains may also have other extended fins, including in females.

Some gallery images have been digitally enhanced to improve image quality. They show the listed type of animal rather than guaranteeing the exact markings of the individual supplied, so natural colour and pattern can vary. The illustrations show representative Red Wagtail Swordtail scenes and do not set the animal’s sex or dispatch size.

This form belongs with our broader livebearer collection. Compare forms by their adult space, water and social requirements rather than treating the selected dispatch length as a different care category.

Check these points before selecting a size

• Adult plan: reserve a base of at least 120 × 30 cm and about 108 litres, whichever dispatch size you select.
• Water: prepare 22–27°C, pH 7.0–8.0 and 10–12 dGH before introduction.
• Companionship: plan at least three using OATA’s suggested ratio of two females to each male.
• Purchase unit: increase the purchase quantity deliberately when assembling a group because each purchase supplies one fish.

Plan the aquarium around the adult size

Use an aquarium with a base measuring at least 120 × 30 cm, or an equivalent footprint, and a volume of about 108 litres or more. Seriously Fish presents this as the smallest aquarium that should be considered for the species. The 14 cm adult length and active swimming behaviour make floor plan and uninterrupted swimming room decisive parts of the choice.

Do not judge suitability from litres alone. A deep aquarium can hold a substantial volume while remaining too short for sustained movement. Start with the 120 cm length and 30 cm width, then confirm that the completed aquarium provides about 108 litres or more after accounting for its design. Leave open swimming space alongside planted cover instead of filling the entire footprint with dense ornaments.

Apply the minimum to common decisions

• A shorter aquarium with a similar volume: choose a longer aquarium because the stated minimum includes the 120 × 30 cm footprint.
• A dispatch-size fish: use the full adult plan from the start rather than moving it through progressively larger aquariums.
• A larger group: increase space beyond the minimum because OATA advises that more groups require more volume.
• A heavily decorated aquarium: retain a clear swimming route while using plants, wood or other shelter around it.

FishBase also records male aggression towards other males, while Seriously Fish describes male dominance hierarchies in confined spaces. Extra water volume cannot compensate for an awkwardly short or crowded layout. Space must let fish move away from one another and use both cover and open water.

Review the final footprint after substrate, plants, wood and other décor are positioned. A suitable plan combines adult-scale length, open swimming room, shelter and stable filtration rather than relying on a nominal litre figure. If the intended group or companion fish make that layout crowded, choose a larger aquarium before adding livestock.

Hold water within the cross-source overlap

Keep the aquarium at 22–27°C, pH 7.0–8.0 and 10–12 dGH. This is the overlap of three relevant ranges: Seriously Fish gives 16–28°C, pH 7.0–8.0 and 10–25 dGH for aquarium care; FishBase records 22–28°C, pH 7.0–8.0 and 9–19 dH in the species’ environment; OATA gives swordtails 22–27°C, pH 7.0–8.0 and 4–12 dH. The OATA component is not a species-specific optimum.

Test the aquarium rather than assuming that tap water, an existing community aquarium or a heater setting falls within those limits. Our water chemistry guide explains what the measurements mean, while the water matcher helps compare measured values with this care range.

Use each result to make one decision

• Temperature below 22°C or above 27°C: stabilise the aquarium inside the routine range before introduction.
• pH below 7.0 or above 8.0: do not add the fish until the aquarium can remain within range.
• Hardness below 10 dGH or above 12 dGH: prepare water that stays inside the shared care range rather than relying on short-term readings.
• Values that move between tests: investigate the aquarium and replacement water before increasing the livestock population.

Measure temperature directly and test pH and hardness with suitable aquarium tests. Record the results so gradual movement is visible instead of waiting for a reading to cross a limit. The target is a consistently suitable environment, not repeated movement from one edge of the range to the other.

Water suitability also includes waste control. Temperature, pH and hardness can all look correct while ammonia or nitrite makes the aquarium unsafe. Treat the routine range as one part of a mature, filtered system and combine it with the zero-ammonia and zero-nitrite checks in the maintenance routine.

Combine open water, cover and biological filtration

Provide open swimming space together with planted shelter. Seriously Fish notes that décor is not especially critical but describes heavily planted aquariums, dark substrate, floating plants and driftwood roots or branches as suitable choices. It also records an appreciation of some water movement without requiring particularly strong filtration.

Arrange taller plants, wood and shelter around the margins or rear so they do not break up the entire swimming run. Floating plants and branches can diffuse light, while rooted plants provide cover. OATA recommends gravel or sand and ideally live plants; plastic plants and suitable ornaments can provide shelter where live plants are not used. Check that every ornament is suitable for aquarium use and leaves enough room for a 14 cm adult to turn and pass.

A filter is essential. The RSPCA explains that a working biological filter supports beneficial bacteria that convert toxic ammonia to nitrite and then to the safer nitrate. Prepare and mature that filter before the fish arrives; our first tropical aquarium guide sets out the preparation sequence.

Match filter flow to the aquarium

For an aquarium of about 108 litres, Seriously Fish gives a turnover of four to five times the aquarium volume each hour and a filter rating of 430–540 litres per hour. Use that specific example when comparing filters for the minimum aquarium. A different aquarium volume needs a filter matched to its own capacity while still leaving the fish able to use open water and sheltered areas.

• Plants moving gently: this is consistent with providing a degree of water movement.
• Fish continually struggling against flow: redirect or reassess the current while maintaining effective filtration.
• Dead areas collecting waste: adjust the layout and maintenance access rather than packing in more décor.
• Reduced filter output: check for blockages and clean the media using removed aquarium water.

Feed a balanced omnivorous diet

Use a good-quality dried food as the staple and add small live, frozen or freeze-dried foods for variety. Seriously Fish describes the species as a generalised omnivore whose wild diet includes aquatic and terrestrial invertebrates, organic detritus, algae and other plant material. It recommends quality dried products together with foods such as Daphnia, Artemia and chironomid larvae or bloodworm.

OATA advises feeding swordtails once a day and giving only what they can eat within a few minutes. Its examples are good-quality flake or granules with a high algae content, supplemented with small live or frozen items such as daphnia, small bloodworm or tubifex. This schedule supplies the portion and frequency rule without turning any one supplement into the complete diet.

Build each feed around a clear limit

• Daily staple: offer a measured portion of suitable flake, granules or another balanced dried product.
• Variety: rotate small live, frozen or freeze-dried invertebrate foods rather than repeating only one item.
• Portion: stop at the amount the fish consume within a few minutes.
• Leftovers: reduce the next portion because uneaten food breaks down and adds waste to the water.

Observe every fish during feeding. An active individual repeatedly missing food may need the portion distributed across more than one part of the aquarium, but keep the total within the few-minutes limit. A fish that suddenly loses interest in food needs a water-quality check and a wider health assessment rather than a larger feed.

Keep diet and filtration decisions connected. Adding more fish increases both feeding and waste, so OATA advises increasing aquarium populations slowly while beneficial filter bacteria adjust. Do not use appetite as a reason to keep adding food after the timed portion has been consumed. Consistent portions, varied ingredients and prompt attention to leftovers protect both nutrition and water quality.

Test weekly and protect the filter bacteria

Keep ammonia at zero mg per litre and nitrite at zero mg per litre. OATA also advises that nitrate should not exceed 20 mg per litre above the normal tap-water level. Test at least once per week and test again when behaviour, breathing, appetite or appearance changes.

At least once every week, change 25% of the aquarium water. Keep the frequency attached to the instruction: the change is 25%, performed at least weekly. Use a siphon to remove solid waste from the substrate where needed, and treat replacement tap water with conditioner to remove chlorine or chloramine before it enters the aquarium.

Maintain the filter without stripping its biology

• Check flow: inspect the filter for blockages whenever output falls.
• Clean only when needed: rinse filter media lightly in aquarium water removed during a partial water change.
• Protect bacteria: do not run the filter media under the tap because chlorine or chloramine may kill the established bacterial population.
• Retest after a concern: confirm ammonia and nitrite remain at zero before adding more fish.

Increase the aquarium population slowly. OATA explains that beneficial bacteria need to increase when more fish and food are added. Adding too many fish too quickly can leave the filter unable to process the extra waste, causing ammonia and nitrite to rise and creating new tank syndrome.

Use a simple written log for temperature, pH, hardness, ammonia, nitrite, nitrate and water changes. The log makes a gradual trend easier to see and links a changed reading to recent feeding, stocking or maintenance. When a result is unexpected, repeat the test carefully before making the next livestock decision.

A larger aquarium usually provides more stable temperature and water quality, but it still needs the same routine. Volume does not replace testing, filtration or water changes. Keep the weekly schedule consistent, protect the biological filter and address waste readings before they affect the fish.

Follow the arrival sequence before release

Prepare the mature aquarium before the parcel reaches you, with temperature, pH and hardness already within the stated range and ammonia and nitrite at zero. Keep the arrival procedure itself focused on the steps in the Tropical Fish Co delivery and Live Arrival Guarantee policy.

Use this order when the parcel arrives

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

The continuous video shows the sealed parcel, its opening and the fish inside the sealed bag before anything is disturbed. Keep the order number with the recording. For a Live Arrival Guarantee claim, contact us the same day with the order number and video so the claim can be assessed under the current policy.

After release, follow OATA’s advice to increase livestock numbers slowly. The established filter bacteria must adjust as fish numbers and feeding rise. Do not combine a new group, several companion species and heavier feeding into one sudden change.

Check the aquarium after introduction

• Water first: confirm ammonia and nitrite remain at zero as the biological load changes.
• Feeding: use the normal once-daily, few-minutes portion rather than adding extra food to encourage activity.
• Social behaviour: watch whether any male competition or boisterous chasing prevents another fish from feeding or using shelter.
• Appearance and breathing: compare each fish with its condition after release and investigate any change promptly.

Respond to changes with water tests first

Test water quality when swimming, colour, temperament, breathing, appearance, body condition or feeding changes. OATA identifies warning signs including hanging at the surface, sitting on the bottom, erratic swimming, darker or paler colour, increased aggression, unusual hiding, altered gill movement, white spots, fluffy growths, damaged fins or scales, changing body condition and reduced interest in food.

Start with measured results rather than guessing at a disease. Check temperature, pH and hardness against 22–27°C, pH 7.0–8.0 and 10–12 dGH, then confirm ammonia and nitrite are zero. Review recent changes in stocking, feeding, filter flow and maintenance because each can affect water quality or social pressure.

Match the sign to the first action

• Surface hanging or changed breathing: test water immediately and inspect filter operation.
• Sitting low or erratic swimming: compare all core water readings and observe whether another fish is chasing it.
• Reduced appetite: remove leftovers, test water and check whether the fish can reach food without interference.
• Fin or scale damage: observe interactions and provide separation while the group and companions are reassessed.
• White spots, fluffy growths or worsening condition: record the signs and contact us for further health guidance.

Keep observations specific. Note which fish changed, when the change began, its measured water values and whether eating, breathing or social behaviour also changed. This makes it easier to distinguish an aquarium-wide water problem from pressure affecting one individual.

Do not respond to every change by feeding more or adding livestock. A larger feed increases waste, while a new companion changes both biological load and social behaviour. Stabilise the aquarium, protect the filter bacteria and continue observing before making another stocking decision.

Plan the group around sex ratio and space

Plan at least three swordtails, using two females to each male. OATA recommends this ratio to reduce stress on females and other aquarium inhabitants and permits larger groups when the same ratio is maintained. More fish require more space, filtration capacity and gradual introduction.

Do not treat the suggested group as three interchangeable fish. FishBase states that males are aggressive towards one another, and Seriously Fish explains that males in confined spaces tend to form dominance hierarchies and may spend substantial time maintaining their positions. The ratio, aquarium footprint and availability of cover therefore matter together.

Assess a proposed group before adding it

• One male and two females: this follows OATA’s suggested ratio for a group of three.
• More than one male: provide a larger, structured aquarium and watch for sustained competition.
• An uncertain ratio: confirm the group’s composition before relying on it to reduce pressure.
• A larger group: increase the aquarium beyond the 120 × 30 cm minimum and add fish gradually.

Ornamental fin shape needs careful interpretation. Seriously Fish notes that the characteristic lower tail extension is associated with adult males, but some ornamental strains may carry other extended fins, including in females. Use the gonopodium or triangular anal fin distinction described by OATA when assessing mature fish rather than relying on colour or a long fin alone.

Watch whether every fish can feed, move through open water and use cover. Occasional movement around another fish is different from repeated pressure that prevents feeding or keeps an individual hidden. If one fish is continually displaced, separate the animals while reassessing the ratio, footprint and shelter.

Because this offer does not guarantee sex, do not assume that selecting several fish automatically creates the recommended ratio. Make the adult group plan first, then assess composition and space as the fish mature.

Screen every community by water and temperament

Choose companions only after matching water, space and temperament. 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. No named species is a universal companion, so assess the actual aquarium and proposed mix.

Use a four-part compatibility screen

A fish sharing the same temperature is not automatically compatible. Its pH and hardness requirements must also overlap, and its behaviour must suit an active livebearer that may become boisterous. Likewise, a peaceful label does not remove the need to consider male competition within the swordtail group.

Introduce livestock gradually so the biological filter can adjust. After each addition, check ammonia and nitrite, observe feeding access and watch whether any fish remains hidden or is repeatedly chased. Pause further additions if water quality or behaviour changes.

When assessing a proposed community, ask us for a stocking and compatibility assessment with the aquarium’s dimensions, volume, measured water values, current inhabitants and intended group composition. Those details allow the decision to be based on the actual space and water rather than a general list of names.

If chasing begins, identify who is pursuing whom and whether the affected fish can feed and use shelter. Separate fish when damage or persistent exclusion occurs, then reassess the mix. Watch fins directly after an introduction instead of assuming that damage has one particular cause.

Answer common Swordtail Red Wagtail questions

How big does a Swordtail Red Wagtail get?

Plan for 14 cm. FishBase records a maximum length of 14 cm, so every dispatch size needs an adult-scale aquarium.

What size aquarium does a Swordtail Red Wagtail need?

Use a base of at least 120 × 30 cm, or an equivalent footprint, and about 108 litres or more, as recommended by Seriously Fish.

How many Swordtail Red Wagtails should I keep together?

OATA’s swordtail group guidance suggests at least three, using two females to each male to reduce stress on females and other inhabitants.

Is a Swordtail Red Wagtail suitable for beginners?

Yes. OATA describes most swordtails as easy to keep, provided the aquarium is mature, filtered, correctly sized and maintained within the stated water range.

What does a Swordtail Red Wagtail eat?

Feed a quality dried product with small live, frozen or freeze-dried foods such as Daphnia, Artemia or bloodworm; offer only what it eats within a few minutes once a day.

What temperature and pH does this fish need?

Keep this fish at 22–27°C and pH 7.0–8.0, with 10–12 dGH; these values are the overlap of FishBase, Seriously Fish and OATA.

Is it aggressive or likely to nip fins?

This fish is generally peaceful, but males can be aggressive towards one another and large swordtails may chase timid tankmates. Watch fins and feeding access after every introduction.

Which kinds of animals can it live with?

This fish can share an aquarium with generally peaceful species after confirming they suit 22–27°C, pH 7.0–8.0, 10–12 dGH and will not be stressed by boisterous chasing.

How does this fish arrive alive in the UK?

Start filming the sealed parcel before opening it. Open and inspect it that day in one continuous take, keep the fish inside the sealed bag on camera, then float the bag for 20–30 minutes before release and do not pour bag water into the aquarium.

Consult the care and welfare references

• FishBase: Xiphophorus hellerii — accepted identity, distribution, recorded environment, adult length, habitat, diet and male behaviour.
• Seriously Fish: Xiphophorus hellerii — aquarium footprint, volume, water range, filtration, décor, diet and social behaviour.
• OATA: How to look after platies and swordtails — group care, feeding, companionship, maintenance and health observations.
• RSPCA aquarium environment guidance — biological filtration and waste processing.
• Tropical Fish Co delivery and Live Arrival Guarantee policy — packing, receipt, filming, floating and claim procedure.