Yellowtail Redtail Catfish (Phractocephalus hemioliopterus)

Decide whether you can house this giant catfish

The Yellowtail Redtail Catfish (Phractocephalus hemioliopterus) is a freshwater, bottom-associated member of the long-whiskered catfish family Pimelodidae. It comes from South America’s Amazon and Orinoco river basins. FishBase records a maximum adult length of 135 cm. This is therefore a fish for an advanced keeper with a purpose-built, public-aquarium-scale system and a credible plan for its full adult size.

Its broad head and long barbels give it the familiar redtail catfish shape, but the decisive feature for care is scale. A small dispatch fish is still a member of a giant species. The aquarium, filtration, furnishings, feeding routine and compatibility plan must all be chosen for the adult rather than treated as upgrades to arrange later.

We classify this fish as advanced because the adult needs exceptional water volume, large-scale biological filtration, secure furnishings and tightly controlled stocking. It is not a suitable first community fish. Keepers comparing more manageable catfish can browse the catfish and plecos collection before committing to this species.

Make the space decision before ordering

Plan for a system around 360 cm long, 240 cm wide and 120 cm high, holding 10,368 litres. Seriously Fish treats those dimensions as an absolute minimum for a fully grown fish and warns that even this volume would not give it the cruising space it has in the wild. The requirement is therefore closer to a public aquarium exhibit than a conventional large home aquarium.

The footprint matters as much as the litre figure. A 360 × 240 cm base covers 8.64 square metres, giving the fish room to turn and move along the enclosure. A narrower vessel with a similar calculated volume would not reproduce the quoted dimensions. Confirm the internal dimensions, usable water volume, access routes and structural provision before treating any system as suitable.

Keep routine aquarium water at 22–26°C, pH 6.0–6.8 and 4–10 dGH. These targets are the overlap of FishBase’s recorded environment, the Seriously Fish species profile and OATA’s freshwater-catfish guidance. They keep routine values inside the species-level ranges while narrowing them with the UK group guidance. Ammonia and nitrite must remain at zero mg per litre.

Use these numbers as pass-or-stop checks

• Adult length: plan around 135 cm, not the selected dispatch size.
• Enclosure: provide at least the quoted 360 × 240 × 120 cm dimensions and 10,368-litre volume.
• Water: maintain 22–26°C, pH 6.0–6.8 and 4–10 dGH.
• Stocking: begin with a plan for one redtail catfish because it is territorial towards its own kind and other large Pimelodids.

If any of these commitments depends on a future move or an uncertain upgrade, postpone the fish until the full facility is ready.

Understand the animal and offer

One purchase supplies one Yellowtail Redtail Catfish in the size selected. The live size selector lists 3,5 - 5 cm, 5 - 6 cm and 8 - 10 cm. The size you select is the size supplied, not the adult size. Every selection still requires a lifelong plan for a fish reaching 135 cm.

Sex is guaranteed only when the selected option explicitly states male or female. This Yellowtail Redtail Catfish listing has no sex-guaranteed option.

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

In nature, adults eat fish, crabs and fruit. Seriously Fish likewise describes an opportunistic predator that takes fish, invertebrates and fallen fruit, while also calling the species quite peaceful in general behaviour. These points belong together: a calm-looking fish may still treat smaller animals as food, so temperament cannot make a smaller companion safe.

Commit only when every part of the plan is ready

• The enclosure meets the adult dimensions rather than merely holding the dispatch fish.
• The mature biological filter can support a very large predatory catfish.
• The feeding plan uses varied appropriate foods and reduces meal frequency as the fish grows.
• The stocking plan excludes smaller fish and accounts for territorial behaviour towards related giant catfish.
• The keeper can carry out large weekly water changes and regular water testing at the quoted system volume.

This combination of adult size, space and workload is why the fish belongs with a small number of highly prepared keepers rather than in an ordinary predator aquarium.

Plan the aquarium around the adult size

Build the lifelong enclosure before relying on a juvenile holding arrangement. FishBase’s recorded adult maximum is 135 cm total length, which is the planning figure used throughout this care information. Seriously Fish separately records 134 cm standard length. Both figures describe an exceptionally large fish, and neither supports treating the smaller dispatch grades as long-term aquarium sizes.

The quoted adult enclosure is around 360 × 240 × 120 cm and 10,368 litres. Treat each dimension as functional space. The 360 cm length provides a movement path, the 240 cm width contributes turning room, and the 120 cm depth forms part of the required water volume. Seriously Fish still considers that enclosure unable to reproduce the wild cruising space of a fully grown animal, so it is a minimum planning point rather than a generous endpoint.

Check the facility in the right order

1. Confirm the permanent location. Reserve enough floor area for the 8.64-square-metre base before allowing for access, filtration and maintenance equipment.
2. Confirm usable internal space. Furnishings must not remove so much open water that the quoted dimensions cease to be meaningful.
3. Plan maintenance access. The keeper must be able to reach, siphon and inspect the enclosure without leaving areas where waste cannot be removed.
4. Secure the contents. Large wood, branches or smooth rocks must be too heavy for the fish to move or fixed securely.
5. Make the adult plan immediate. Do not base the purchase on the time a smaller fish might spend in a lesser aquarium.

A weekly 25% water change on 10,368 litres is approximately 2,592 litres. This scale means water storage, conditioning and safe drainage need to be engineered into the facility rather than handled with a few household buckets.

Never release an unwanted giant fish into rivers or ponds. Seriously Fish notes that public aquaria may already receive more donated adults than they can accept, so rehoming cannot replace a lifelong plan made before purchase.

Hold water inside the overlapping ranges

Keep the aquarium at 22–26°C, pH 6.0–6.8 and 4–10 dGH. FishBase records 20–26°C, pH 5.5–6.8 and hardness up to 10 dGH for the species’ environment; Seriously Fish gives 21–26°C, pH 6.0–7.5 and 2–12 dGH for aquarium care. OATA’s freshwater-catfish sheet gives 22–27°C, pH 6.0–8.0 and 4–18 dGH for the group. The recommended targets are the overlap of all three.

Keep ammonia and nitrite at zero mg per litre. OATA also says nitrate should not exceed 20 mg per litre above the normal tap-water level. These waste values are active management limits: test them rather than judging water quality from clarity or smell.

Use the water chemistry guide to understand each test and record the results with dates. The water matcher can then compare those measured values with the stated range. Base the decision on actual aquarium readings, not an estimate drawn from the local water area.

Test the replacement water as well as the enclosure when results change unexpectedly. The purpose is to distinguish a source-water difference from waste accumulating inside the aquarium, allowing the correct part of the system to be addressed.

Mature and size the biological filter

Use a well-established, efficient biological filter and keep it running as an essential part of the enclosure. The RSPCA explains that fish release toxic ammonia; a working biological filter supports bacteria that convert ammonia to nitrite and then to the safer nitrate. OATA also requires a filter in every catfish aquarium and warns that stocking too quickly can overwhelm the bacterial population.

Prepare the system before the fish arrives. The first tropical aquarium guide explains how to prepare and mature a filter before livestock is introduced. For this species, maturity is only the first condition: the filter must also be appropriate for a fish that becomes exceptionally large and eats substantial meaty foods.

Use test results to judge the filter

• Ammonia at zero and nitrite at zero: the readings meet OATA’s stated limits, so continue testing and maintenance.
• Either reading above zero: the biological system is not keeping waste within the required limits. Do not add further livestock or increase feeding.
• Rising nitrate: use the weekly water-change routine and waste removal to prevent it exceeding 20 mg/l above the tap-water level.
• Reduced flow: check the filter for blockages rather than assuming clear water means the system is functioning correctly.

Increase aquarium stocking only slowly because beneficial bacteria must increase when more fish and more food are added. In this enclosure, however, the compatibility plan already centres on one redtail catfish. The slow-stocking rule is not permission to add unsuitable companions; it protects water quality only after every animal has passed the separate space, predation and territorial checks.

Give filtration equipment enough access for inspection and cleaning. A blocked or inaccessible filter cannot be maintained reliably, while furnishings placed across intakes or access points make routine work harder. Arrange the permanent system so the keeper can check flow, remove waste and reach filter media without dismantling the animal’s main swimming space.

Choose furnishings that cannot be swallowed or moved

Keep the adult enclosure open, secure and simple. Seriously Fish says décor is not essential for an adult when the lighting is fairly dim. Large pieces of bogwood, beech branches or smooth rocks can be used, but they must be too heavy for the fish to move or secured in place. Preserve plenty of open swimming space around every item.

Juveniles can use hiding places formed by bogwood, tangles of roots and branches, rock piles or plastic pipe of a suitable bore. Choose any pipe or opening around the fish’s current body size so it can enter and leave freely. Reassess these shelters as the animal grows; an item that no longer functions safely as a shelter should not remain simply because the fish used it when smaller.

Choose the base deliberately

Test the furnishing plan against the adult rather than the dispatch fish. A lightweight ornament that appears stable beside a small juvenile does not satisfy the instruction that adult furnishings be too heavy to move or securely fixed. Likewise, a decorative layout that occupies most of the floor conflicts with the need for open swimming space.

Use smooth materials where the profile names them and position branches or wood so routine siphoning remains possible. The aim is not to create a crowded display. It is to provide shelter while useful, maintain an unobstructed route through the enclosure and prevent movable objects from becoming hazards as the fish gains size.

Plants are not required by the species profile. If any are included, do not let them conceal areas where solid waste collects or interfere with access to the biological filter. Cleaning, security and open space remain the governing decisions for this giant catfish.

Feed a varied opportunistic diet

Feed a varied selection of appropriate meaty foods rather than relying on one favourite item. Seriously Fish recommends prawns, mussels, cockle, lancefish and earthworms in captivity. Larger specimens can also take whole fillets of white fish. FishBase records adults eating fish, crabs and fruit in nature, confirming that this is an opportunistic feeder rather than a species with one narrow wild food.

For a juvenile, feed every other day. Reduce meal frequency as the fish grows; an adult needs only a single meal per week at most. Offer a controlled meal and take care not to overfeed. Seriously Fish warns that predatory fish can become overweight when given excessive high-protein food, leading to long-term health problems.

Build variety without increasing frequency

• Rotate among prawns, mussels, cockle, lancefish and earthworms instead of serving the same item repeatedly.
• Use white-fish fillets only for a specimen large enough to take them safely.
• Keep each food change within the existing feeding schedule rather than adding extra meals.
• Watch body condition and reduce excess portions rather than assuming a large predator should always look heavily fed.
• Remove uneaten material before it breaks down and damages water quality.

Do not feed beef heart, chicken or other mammal meat. Seriously Fish explains that some of the lipids in these meats cannot be metabolised properly by the fish and can contribute to excess fat deposits. This is a direct food exclusion, not merely a preference for another protein.

Variety also prevents the fish becoming so accustomed to one food that it refuses alternatives. If interest narrows to a single item, restore rotation among the named foods instead of increasing that preferred food’s frequency. A varied schedule protects both nutrition and feeding flexibility.

Link feeding decisions to water testing. OATA warns that overfeeding leaves uneaten food to break down and release toxic waste. If ammonia or nitrite appears, do not conceal the problem with more food or additional animals. Restore water quality and review the portion offered, the waste-removal routine and biological filtration.

Complete the weekly maintenance routine

At least once every week, change 25% of the aquarium water. On the quoted 10,368-litre adult system, that is approximately 2,592 litres, so the facility needs a safe method for preparing, conditioning, moving and draining a very large volume. Schedule a 25% change at least weekly.

Treat replacement tap water with conditioner to remove harmful chlorine or chloramine before adding it to the aquarium. Use a siphon or suitable large-system equivalent to remove solid waste from the base during the water change. A bare base or large smooth pebbles can make accumulated waste easier to locate than ordinary gravel.

Pair each maintenance task with a check

• Water change: replace 25% at least weekly and remove visible solid waste.
• Water tests: test at least weekly for ammonia and nitrite, which must remain at zero mg/l.
• Nitrate comparison: keep the result within 20 mg/l above the normal tap-water level.
• Filter flow: check the filter for blockages.
• Filter media: if cleaning is needed, rinse it lightly in aquarium water removed during the partial change.

Do not run filter media under the tap. OATA warns that chlorine or chloramine can kill the beneficial bacterial population established in the media. Light rinsing in removed aquarium water reduces the amount of bacteria lost while allowing debris to be cleared.

Record the test results and work completed. A written sequence makes trends visible: a nitrate rise, recurring blockage or detectable ammonia can then be recognised as a developing system problem rather than an isolated reading. Respond before adding any animal or increasing feeding.

Inspect the fish during routine work without turning observation into handling. OATA advises watching for changes in swimming, colour, temperament, breathing, appearance, body condition and feeding. If a change appears, test water quality first and contact us for further guidance on the fish’s health.

Follow the arrival procedure in order

The Tropical Fish Co delivery and Live Arrival Guarantee policy says fish are hand-packed in pure oxygen inside an insulated poly box, with a heat pack when the weather calls for it, and carried by a licensed live-animal courier. Someone must be at the address to receive the parcel because live fish cannot be left unattended.

On arrival

1. Start filming before the parcel is opened. Show the sealed parcel with the outer box visible and keep the recording continuous.
2. Open and inspect the parcel on the day it arrives. Keep filming through opening until the fish can be seen inside the sealed bag, before anything is disturbed.
3. Float the bag for 20–30 minutes before releasing the fish.
4. Never pour the bag water into the aquarium.

Film every delivery from the sealed parcel onward. If a Live Arrival Guarantee claim is needed, contact us on the day the fish arrives with the order number and continuous unboxing video showing the sealed parcel, its opening and the fish still inside the sealed bag.

Check the aquarium separately

Before introduction, OATA advises confirming that ammonia and nitrite are zero. The aquarium must already meet 22–26°C, pH 6.0–6.8 and 4–10 dGH, with a mature biological filter running. These checks belong before release because acclimatisation cannot compensate for unsuitable water or an immature filter.

After introduction, look for clear eyes, undamaged fins, intact skin, appropriate swimming and normal interest in food. Watch for altered breathing, unusual surface hanging, prolonged bottom sitting, erratic swimming, darker or paler colour, increased hiding, white spots, fluffy growths, damaged fins or scales, changing body condition and reduced feeding. When any change occurs, test the water values first.

Continue the established schedule through the first month: test at least weekly, change 25% at least weekly and check the filter for blockages. Do not use the fish’s arrival as a reason to add more livestock quickly.

Screen every companion for predation and space

Avoid smaller fish. Seriously Fish says this catfish will readily eat them and notes that even many fish commonly regarded as “tankbusters” remain too small to be safe. A peaceful manner does not cancel predatory feeding behaviour.

Plan to keep one redtail catfish. It is territorial towards its own kind and other large Pimelodid catfish, so it should be the only fish of this type unless space truly is no issue. Given that one adult already needs a system approaching public aquarium scale, this exception demands more than simply meeting the single-fish minimum.

Apply the checks in sequence

Assess invertebrates as potential food because the natural and captive diets include crabs and other invertebrates. That feeding biology is a caution, not a universal list of invertebrates to avoid. The decision still requires the proposed animal’s adult dimensions, behaviour and ability to coexist in the same enormous enclosure.

Do not use current size as the compatibility test. A fish that appears substantial beside a small dispatch catfish may remain far below the redtail catfish’s 135 cm adult maximum. Compare planned adult animals and the finished enclosure, not the individuals seen on the day of introduction.

Stocking slowly protects the biological filter, but it does not turn an unsafe species combination into a safe one. Complete the predation, territory, water and space assessment first; only then apply OATA’s instruction to increase aquarium population slowly.

Limit mixed stocking to the named possibilities

Seriously Fish says similarly sized species can be kept with a redtail catfish in suitable surroundings, but doing so needs an aquarium approaching public-aquarium size. Possible companions named in that profile are doradid catfish such as Oxydoras niger and Pterodoras granulosus. Big characins and cyprinids are another possibility only when the aquarium is also very deep.

These are conditional possibilities, not universal tank mates. Each proposed animal must still fit the shared water range, remain appropriate at adult size and leave enough space for normal movement. The quoted 10,368-litre enclosure is already the absolute minimum planning point for one fully grown redtail catfish, so it must not automatically be treated as a mixed-species capacity.

Use a cautious compatibility plan

• Suitable only after full screening: similarly sized species in suitable public-aquarium-scale surroundings.
• Named possibilities: Oxydoras niger and Pterodoras granulosus.
• Conditional possibilities: big characins and cyprinids when the enclosure is also very deep.
• Avoid: smaller fish that may be eaten.
• Territorial concern: additional redtail catfish and other large Pimelodids unless space truly is no issue.

Observe behaviour after any carefully screened introduction. OATA identifies changes in aggression, hiding, swimming, breathing, colour, body condition and feeding as warning signs. Test ammonia and nitrite when behaviour changes because water-quality stress and compatibility problems require different responses.

Do not add a second fish merely to make the display appear busier. This species has no supported shoaling requirement, and its territorial behaviour points towards a one-redtail plan. Open water, secure furnishings and manageable biological loading are more important than filling the enclosure with additional animals.

The honest uncertainty in a mixed exhibit is that named possibilities still depend on the dimensions and inhabitants of the actual facility. A match is credible only after the adult fish, water range, territory and usable swimming space all pass together.

Answer common buyer questions

How big does a Yellowtail Redtail Catfish get?

FishBase records an adult maximum of 135 cm total length. Plan the permanent enclosure around that figure rather than the fish’s dispatch size.

What size aquarium does a Yellowtail Redtail Catfish need?

Plan for at least 10,368 litres in a system around 360 × 240 × 120 cm. Seriously Fish treats those dimensions as an absolute minimum and says even that does not provide the cruising room it would have in the wild.

How many Yellowtail Redtail Catfish should I keep together?

Plan on one fish. Seriously Fish says it is territorial towards its own kind and other large Pimelodids and should be the only fish of this type unless space truly is no issue.

Is a Yellowtail Redtail Catfish suitable for a beginner?

This fish is an advanced retailer classification because it reaches 135 cm and needs a purpose-built enclosure of at least 10,368 litres, powerful biological filtration and lifelong large-system maintenance.

What does a Yellowtail Redtail Catfish eat?

Feed this fish a varied rotation of prawns, mussels, cockle, lancefish and earthworms; larger specimens can take white-fish fillets. Feed juveniles every other day, reduce frequency with growth and give an adult no more than one meal per week.

What temperature and pH does it need?

Keep this fish at 22–26°C, pH 6.0–6.8 and 4–10 dGH. These targets are the overlap of FishBase’s recorded environment, the Seriously Fish species profile and OATA’s freshwater-catfish guidance.

Is this fish aggressive or does it nip fins?

Treat it as a peaceful predator: Seriously Fish calls it quite peaceful, but it will eat smaller fish and is territorial towards its own kind and other large Pimelodids. Screen companions for predation and territory rather than relying on a general community label.

Which animals can live with it?

Possible companions named by Seriously Fish are similarly sized species, including Oxydoras niger and Pterodoras granulosus, in public-aquarium-scale surroundings. Big characins and cyprinids are possibilities only when the aquarium is also very deep; avoid smaller fish.

How does it arrive alive in the UK?

Tropical Fish Co’s policy says the fish is hand-packed in pure oxygen inside an insulated poly box, with a heat pack when the weather calls for it, and carried by a licensed live-animal courier. Receive the parcel in person, film continuously from the sealed box and float the bag for 20–30 minutes before release.

Consult the care references

• FishBase: Phractocephalus hemioliopterus species identity, family, distribution, environmental range, diet and maximum recorded length.
• Seriously Fish: Phractocephalus hemioliopterus aquarium dimensions, water conditions, furnishings, feeding and compatibility.
• Ornamental Aquatic Trade Association: How to look after freshwater catfish, covering group water quality, filtration, maintenance, introduction and health observation.
• RSPCA: Aquarium environment guidance covering biological filtration and the conversion of ammonia and nitrite.
• Tropical Fish Co: Delivery, acclimatisation and Live Arrival Guarantee policy.