Rostratum Whiptail Catfish (Sturisoma rostratum)

Choose a long-snouted whiptail for a mature, oxygen-rich tank

The Rostratum Whiptail Catfish (Sturisoma rostratum) is a slender armoured catfish with a long, pointed snout, a tall sail-like dorsal fin and fine filaments trailing from both tips of the tail. It lives on wood and stone in rivers of the lower Amazon basin in Brazil and grazes the algae and biofilm that grow there. For a peaceful, spacious aquarium with clean, moving water it is one of the most striking catfish you can keep.

It belongs to the armoured suckermouth family Loricariidae, subfamily Loricariinae, and is the type species of the genus Sturisoma, the species to which the genus name is anchored. The genus name means "sturgeon body", and rostratum means beaked, after that long snout. The species was first described as Loricaria rostrata.

Know where it comes from

A peer-reviewed revision of the genus (Londoño-Burbano and Britto, 2024) found that S. rostratum is limited to the lower Amazon basin, in the Araguaia, Tocantins, Tapajós, Maranhão and Mearim rivers and their tributaries. Earlier, the name was thought to cover whiptails across most of South America's main river basins. That history means older care notes filed under this name may describe other species, so the advice below uses current sources and says where it borrows from close relatives.

Tell Sturisoma from similar whiptails

These differences come from Planet Catfish, which adds that snout length alone is not a reliable way to separate the two genera. Our Royal Whiptail Catfish is a Sturisomatichthys, while the Black-Nosed Whiptail Catfish and the Bearded Whiptail Catfish are true Sturisoma. See them all among our Sturisoma whiptails.

Know exactly what you receive

One purchase supplies one live Rostratum Whiptail Catfish. The size option is "Standard": the fish is sent at the size currently available, which is smaller than the adult size. Sex is not chosen or guaranteed.

The photographs show the type of fish, not the individual you will receive. Pattern and shade vary between fish and change with lighting and background, so expect some difference.

Decide between one fish and a pair

• One fish: a peaceful centrepiece grazer for a large community tank.
• Two or more: possible in a roomy tank with plenty of grazing surfaces, because whiptails are gregarious and mainly defend territory when breeding.
• A pair for breeding: in Sturisoma, mature males grow bristles (odontodes) along the sides of the head, and ScotCat describes females of the related S. barbatum as heavier-bodied. Young fish cannot be sexed.

Prepare the aquarium before ordering and check our delivery page for dispatch days and the Live Arrival Guarantee.

Plan the aquarium around a 19 cm adult

FishBase and Planet Catfish give a maximum of 19 cm standard length. Standard length stops at the base of the tail, so the tail filaments add more. This is a long fish that likes to stretch out on wood and stone, and it needs room to do so.

No published source gives a minimum aquarium for S. rostratum itself. ScotCat recommends a tank at least 90 cm (3 ft) long, lightly stocked, for the larger S. barbatum, and Neale Monks in Tropical Fish Hobbyist says Sturisoma need a spacious tank. We use 90 cm as the minimum length here; a bigger tank holds oxygen and water quality more steadily.

Run a three-step space check

1. Measure the length: at least 90 cm, with enough width for wood, stones and open water.
2. Keep stocking light: ScotCat stresses an under-stocked tank, because these catfish suffer when waste builds up.
3. Size the equipment for the real volume: choose the filter, circulation pump and heater for the actual water volume, not the label.

Give it wood, smooth stone and current

Monks explains that Sturisoma belong to a whiptail group that lives on solid surfaces such as wood and rock, often in flowing water, and grazes the algae growing there. ScotCat advises large flat stones or roots so the fish can sprawl out at full length. Planet Catfish notes that the habitat of the related Amazonian S. nigrirostrum has no plants apart from floating ones, and that the fish feeds on biofilm from stones and driftwood.

Divide the tank by function

Monks also recommends a mature aquarium with good light so that algae grows for the fish to graze. Let the tank run with its lights on for some weeks before the fish arrives so the wood and stones carry a film to graze. Secure all wood and stone firmly so nothing shifts when the fish rests on it.

Hold the water warm, soft to medium and stable

No published water values exist for S. rostratum. The best guide is its close Amazonian relative S. nigrirostrum, which Planet Catfish lists at 24–28°C and pH 6.0–7.0 in naturally soft water. Monks warns that the commonly kept Sturisoma do not tolerate very warm water, and ScotCat gives 22–24°C for the southern S. barbatum. Putting those together, we suggest 24–26°C: within the Amazonian relative's range and away from its warmest end.

Match your tap water to the range

The 15 dH upper hardness is Planet Catfish's figure for S. barbatum; the waste limits are from OATA's catfish guidance. ScotCat stresses keeping nitrate down with regular water changes, because these catfish decline quickly when it climbs. If your tap water is very hard, mixing in some reverse-osmosis water at every change helps keep the values steady. Use our water matcher to compare your readings, and treat every change with a dechlorinating conditioner.

Move plenty of water and oxygen

This is the part of Sturisoma care most often underestimated. Monks writes that brisk currents and ample oxygen are essential for this group, and that they are very sensitive to the stagnant, oxygen-poor water of overstocked or poorly kept tanks. ScotCat likewise calls for a good current and filtration that keep oxygen high.

Use a filter rated well above the tank volume and add a circulation pump if needed, aimed along the length of the tank so water moves past the wood and stones and the surface keeps rippling. Monks notes that the circulation pumps sold for reef tanks create strong currents easily. Our guide to aquarium filtration explains flow rates and media.

Follow a weekly routine

1. Test ammonia, nitrite and nitrate before maintenance.
2. Change up to 25% of the water, the weekly figure OATA gives, and more often if nitrate rises.
3. Siphon the sand and the base of the wood.
4. Check the filter and pump for blockages and lost flow.
5. Rinse media in tank water, never under the tap.

Feed a grazer's diet

Monks describes Sturisoma as largely herbivorous and says they really need green algae in their diet, with algae wafers, spirulina flake, sliced courgette and cooked spinach as good foods. ScotCat lists algae and green foods such as lettuce, peas, cucumber and courgette for the related S. barbatum, with occasional flake and frozen bloodworm.

Build one measured meal

• Grazing: algae and biofilm on wood and stones, kept growing with good light.
• Staple: an algae or spirulina wafer that sinks and stays whole long enough to be grazed.
• Vegetables: a slice of blanched courgette or cucumber, weighted down and removed within a day.
• Occasional protein: a little thawed frozen bloodworm for variety.
• Timing: feed at the same place each time, with a portion after lights-out if other fish are quick.

Our algae control guide explains how to keep useful algae on surfaces without letting it take over the glass. A grazer does not replace good maintenance, and heavy algae usually means too much light or too many nutrients. The pleco care guide covers feeding other suckermouth catfish in the same way.

Introduce it to a settled aquarium

Add this whiptail only to a mature, fully cycled aquarium with zero ammonia and nitrite, strong circulation and grazing surfaces already in place. A brand-new tank has neither the biofilm it eats nor the stable water it needs.

Follow OATA's method with the lights off: float the sealed bag for about 10 minutes, add small amounts of tank water over up to 20 minutes, then release the fish with as little bag water as possible. Our step-by-step acclimatisation guide shows each stage.

Use a first-week checkpoint plan

Choose calm companions

ScotCat describes Sturisoma as very peaceful and warns against fin-nipping fish, because the long tail filaments attract nipping. Monks adds that whiptails are slow feeders and easy targets for nippy or aggressive fish, while docile midwater fish make the best companions.

Screen each companion

The Twig Catfish is a smaller relative from the same whiptail group with similar needs for clean water and grazing. Check a planned community with our tank mates checker, and browse more grazers among our algae eaters, all catfish and plecos or the wider South American catfish range.

Watch for problems early

Pair each sign with an action

OATA lists clear eyes, intact fins, steady breathing and normal swimming as signs of health. With this fish, falling oxygen is often the first problem, so watch breathing closely on warm days and whenever the filter flow drops.

Breeding notes

Planet Catfish has no breeding report for S. rostratum. Monks says Sturisoma are bred less often than smaller whiptails and spawn on flat surfaces, often vertical ones such as the aquarium glass. Broods are small and the male guards them until the fry swim freely. ScotCat describes the male of the related Sturisomatichthys aureus guarding and cleaning the eggs for up to 8 days.

Monks stresses that brisk currents and plenty of oxygen are essential both for healthy eggs and fry and for getting adults to spawn at all. Once the yolk sacs are used up, the fry are reared on algae, infusoria and finely powdered flake.

Answer Rostratum Whiptail Catfish buying questions

What is a Rostratum Whiptail Catfish?

It is Sturisoma rostratum, a long-snouted armoured whiptail catfish (family Loricariidae) from the lower Amazon basin in Brazil. It is the type species of the genus Sturisoma and a peaceful grazer of wood and stone surfaces.

How big does Sturisoma rostratum grow?

FishBase and Planet Catfish give 19 cm standard length. The long tail filaments add more on top, so plan for a long fish.

What size aquarium does it need?

No minimum is published for this species. ScotCat recommends a tank at least 90 cm long for the larger Sturisoma barbatum, which we use as the minimum here, with more space better.

What water conditions does it need?

There are no published values for S. rostratum itself. We suggest 24–26°C, pH 6.0–7.0 and soft to medium water, based on the Amazonian S. nigrirostrum and on advice that Sturisoma do not tolerate very warm water. Keep it well oxygenated with zero ammonia and nitrite.

Does it eat algae?

Yes. Sturisoma are largely herbivorous and graze algae and biofilm. Algae alone is not enough in most tanks, so add algae wafers, spirulina-based food and vegetables such as courgette.

Is it peaceful?

Yes, Sturisoma are very peaceful. Keep it away from fin-nippers, which target the long tail filaments, and from fish that compete hard for food.

Has it been bred in aquariums?

Planet Catfish has no breeding report for this species. Related Sturisoma lay eggs on flat surfaces such as the aquarium glass, and the male guards them until the fry swim.

How many fish come with one purchase?

One live fish of the standard size currently available.

Consult the care references

• FishBase: Sturisoma rostratum — classification, distribution and maximum length.
• Planet Catfish: Sturisoma rostratum — names, size, distribution and how to tell Sturisoma from Sturisomatichthys.
• Londoño-Burbano & Britto (2024), Taxonomic revision of Sturisoma, Journal of Fish Biology 104: 989–1041 — peer-reviewed revision of Sturisoma confirming S. rostratum as the type species and its lower Amazon range.
• Planet Catfish: Sturisoma nigrirostrum — water values and feeding of a related Amazonian Sturisoma, used because none are published for S. rostratum.
• ScotCat: Sturisoma barbatum factsheet — tank length, current, décor, sexing, diet and breeding notes for the related S. barbatum.
• Tropical Fish Hobbyist: The Weird and Wonderful World of Whiptails — Neale Monks on whiptail catfish care, oxygen and current, feeding, tank mates and breeding by group.
• OATA: How to look after freshwater catfish — UK group-level catfish guidance on water quality, substrate, introduction and handling.
• OATA: How to test water quality in your freshwater aquarium — UK guidance on water testing, conditioners and weekly water changes.
• Tropical Fish Co delivery policy — current dispatch days and Live Arrival Guarantee terms.