Sterbai Corydoras Care Guide — Tank Setup, Feeding and Breeding

Introduction

The Sterbai Corydoras is one of the most popular and visually striking members of the Corydoradinae subfamily, beloved by aquarists worldwide for its bold patterning, peaceful disposition, and entertaining bottom-dwelling behaviour. Originally described by Knaack in 1962 and named in honour of the German aquarist Günther Sterba, this species has become a staple of the community aquarium hobby. It was historically classified under the genus Corydoras but has since been reclassified into the genus Hoplisoma following a major taxonomic revision of the Corydoradinae by Britto and colleagues, though it is still widely referred to as Corydoras sterbai in the aquarium trade.

Native to the upper Rio Guaporé basin in Brazil and Bolivia, this species thrives in warm, soft waters — a characteristic that sets it apart from many other commonly kept corydoras species and makes it an excellent companion for discus, rams, and other warmth-loving tropical fish. Sterbai Corydoras are hardy, readily available as captive-bred specimens, and display fascinating social behaviours when kept in groups. Whether you are a beginner looking for an engaging bottom-dweller or an experienced aquarist seeking a reliable and attractive addition to a planted community tank, the Sterbai Corydoras is an outstanding choice.

Quick Stats

Scientific name	Hoplisoma sterbai (Knaack, 1962)
Common names	Sterbai Corydoras, Sterba’s Corydoras, Sterbai Cory
Family	Callichthyidae
Origin	Upper Rio Guaporé basin, Brazil and Bolivia
Adult size	6–7 cm
Lifespan	8–15 years
Difficulty	Easy
Breeding difficulty	Moderate
Temperature	24–28 °C
pH range	6.0–7.6
General hardness (GH)	2–12 dGH
Carbonate hardness (KH)	1–8 dKH
Minimum tank size	80 litres
Conservation status	Least Concern (IUCN)

Appearance

The Sterbai Corydoras is among the most handsome of all corydoras species, displaying a striking pattern that is easy to distinguish from its close relatives. The body is dark brown to near-black and is covered with a dense network of white or cream-coloured spots that radiate across the head, flanks, and dorsal surface. On the head, these spots tend to form reticulated lines that run from the snout back towards the gill plates, creating an almost maze-like pattern. As the eye moves towards the tail, the spots become more regularly spaced and defined, forming neat rows along the flanks.

One of the most eye-catching features of this species is the bright orange or golden-yellow colouration on the pectoral fin spines and the leading rays of the pelvic fins. This warm accent colour contrasts beautifully against the dark body and is often the feature that first draws aquarists to the species. The dorsal fin typically displays a dark base with lighter spotting, while the caudal fin carries vertical bands of dark and light pigment. The adipose fin, characteristic of callichthyid catfish, is small and usually carries a dark blotch.

Like all corydoras, the Sterbai possesses two rows of overlapping bony scutes along each flank rather than traditional scales, giving the body a slightly armoured appearance. The mouth is positioned ventrally and is flanked by two pairs of sensitive barbels, which the fish uses to forage through the substrate in search of food. Males tend to be slightly smaller and more slender than females when viewed from above, while mature females develop a noticeably rounder belly, particularly when gravid with eggs. Both sexes display the same vibrant patterning, with no significant sexual dimorphism in colour.

It is worth noting that the Sterbai Corydoras is sometimes confused with the closely related Hoplisoma haraldschultzi (Harald Schultz’s Corydoras), which displays a superficially similar pattern but in reverse — light spots on a dark background versus dark spots on a lighter ground. Careful observation of the patterning direction and the distinctive orange pectoral fin spines of the Sterbai will help distinguish between the two.

Varieties and Morphs

While the wild-type Sterbai Corydoras remains by far the most commonly available form, selective breeding in captivity has produced a small number of recognised colour morphs that occasionally appear in the aquarium trade.

The albino Sterbai Corydoras is the most widely available variant. This morph lacks the dark melanin pigmentation of the wild type, resulting in a pale pinkish-white body with the characteristic orange-yellow pectoral and pelvic fin colouration retained and often appearing even more vivid against the lighter background. The eyes are typically red or pink. Albino specimens are equally hardy as their wild-type counterparts and can be kept together without any compatibility concerns.

A leucistic form is occasionally encountered, displaying a washed-out or faded version of the wild-type pattern with reduced dark pigment but retaining dark eyes. This variant is less common than the true albino and is sometimes sold under the trade name “super white” or “platinum” Sterbai, though these names are not standardised.

Beyond these two morphs, genuinely distinct captive-bred variants of the Sterbai Corydoras are rare. Any dramatic variation in patterning seen in the trade is more likely to reflect natural individual variation or, in some cases, misidentification of closely related species rather than a true selectively bred morph.

Natural Habitat

The Sterbai Corydoras originates from the upper Rio Guaporé (known as the Río Iténez in Bolivia), a major tributary of the Rio Madeira within the Amazon basin. This river system forms part of the border between the Brazilian state of Mato Grosso and the Beni Department of Bolivia. The region is characterised by tropical lowland forest, seasonal flooding, and a network of slow-moving tributaries, streams, and floodplain lakes.

In its natural habitat, this species is found in shallow, slow-flowing waters with sandy or fine-gravelled substrates, often with a layer of leaf litter, fallen branches, and submerged vegetation providing cover. The water tends to be warm, soft, and slightly acidic, influenced by the decomposition of organic matter and the lack of significant mineral content in the surrounding soils. Temperatures in the upper Guaporé frequently reach 26–28 °C, which is notably warmer than the habitats of many other commonly kept corydoras species. This tolerance for higher temperatures is one of the key characteristics that makes the Sterbai Corydoras such a versatile aquarium fish.

Sterbai Corydoras are social fish in the wild, typically encountered in loose groups that forage together across the riverbed, sifting through sand and detritus for small invertebrates, insect larvae, and organic matter. They share their habitat with a wide range of other Amazonian species, including characins, dwarf cichlids, and other catfish. Understanding these natural conditions is key to replicating a suitable environment in the home aquarium.

Tank Size and Setup

A group of six Sterbai Corydoras can be comfortably housed in an aquarium of at least 80 litres, though a larger tank of 120 litres or more is recommended if you plan to keep a bigger group or maintain them in a community setting. As with all corydoras, these fish are highly social and should never be kept singly or in pairs. A group of six is the absolute minimum, and groups of eight to twelve or more will bring out the most natural and entertaining behaviours. The tank footprint is more important than height, as these are strictly bottom-dwelling fish. A long, shallow tank with a generous base area is preferable to a tall, narrow design.

The substrate is arguably the single most important consideration when setting up a tank for Sterbai Corydoras. These fish spend the vast majority of their time in direct contact with the substrate, using their sensitive barbels to sift through it in search of food. A fine, smooth sand substrate is the ideal choice. Sharp or coarse gravel can damage or erode the barbels over time, leading to infections and reducing the fish’s ability to feed naturally. Play sand, pool filter sand, or purpose-made aquarium sand in a natural colour all work well. Avoid substrates with jagged edges or large particle sizes.

Décor should aim to replicate the sheltered, shaded environment of the species’ natural habitat. Driftwood, smooth river stones, and dried leaf litter such as Indian almond or oak leaves create a natural aesthetic while providing cover and releasing beneficial tannins that gently soften and acidify the water. Live plants are an excellent addition and help to maintain water quality. Species such as Anubias, Java Fern, Cryptocoryne, and Amazon Sword are all well-suited to the warm, soft water conditions that Sterbai Corydoras prefer. Floating plants can be used to diffuse overhead lighting, which these somewhat shy fish will appreciate.

Ensure the tank has some open areas of substrate where the group can forage freely. A layout that combines open sandy areas with clusters of planting and driftwood refuges will provide the best balance of foraging space and security. Corydoras often rest together in shaded spots during quiet periods, so providing a few such retreats is important for their well-being.

Water Parameters

The Sterbai Corydoras is relatively adaptable in terms of water chemistry, but it thrives best when conditions approximate those of its natural habitat. The species’ notable tolerance for warmer water — comfortably up to 28 °C — distinguishes it from many other corydoras and makes it one of the few species in the genus truly suited to life alongside discus and other heat-loving tropicals. Stability in water parameters is more important than hitting an exact number, and gradual adjustments are always preferable to sudden changes.

Temperature	24–28 °C
pH	6.0–7.6
General hardness (GH)	2–12 dGH
Carbonate hardness (KH)	1–8 dKH
Ammonia	0 ppm
Nitrite	0 ppm
Nitrate	Below 20 ppm

Ammonia and nitrite must always be maintained at zero, as corydoras are sensitive to poor water quality despite their reputation as hardy fish. Nitrate should ideally be kept below 20 ppm through regular partial water changes, typically 25–30% weekly. The species is somewhat tolerant of a range of hardness values but will display the best colour and health in soft to moderately hard water. If your tap water is very hard, blending with reverse osmosis (RO) water can help achieve more suitable conditions, particularly if breeding is a goal.

Filtration and Equipment

Effective biological and mechanical filtration is essential for maintaining the clean, well-oxygenated water that Sterbai Corydoras require. A quality hang-on-back filter, internal canister, or external canister filter rated for the tank volume will all serve well. The key considerations are thorough biological filtration to process ammonia and nitrite, and gentle to moderate flow at the substrate level. While corydoras are not found in stagnant water in the wild, they are not strong swimmers and do not appreciate being buffeted by powerful currents. If your filter produces a strong output, using a spray bar, lily pipe, or baffle to diffuse the flow is advisable.

Corydoras are facultative air-breathers, meaning they will periodically dash to the surface to gulp atmospheric air, which is absorbed through the intestinal lining. This behaviour is entirely normal and should not be mistaken for a sign of distress, though if fish are doing it constantly and frantically, it may indicate low dissolved oxygen levels. Good surface agitation from the filter outlet will help maintain adequate oxygenation and reduce the frequency of this behaviour. An airstone or sponge filter can provide supplementary aeration if needed.

A reliable heater is important given this species’ preference for warmer water. Choose a heater appropriate for your tank volume, and consider using a heater guard to prevent the fish from resting against it and sustaining burns — a risk that is particularly relevant for bottom-dwelling species. A thermometer placed at the opposite end of the tank from the heater allows you to monitor temperature accuracy.

Lighting should be moderate. Sterbai Corydoras are most active during dawn and dusk in the wild and can be somewhat retiring under very bright lights. If you are growing plants that require strong lighting, the addition of floating plants or shaded resting areas will help the fish feel secure. A standard aquarium LED on a timer set to eight to ten hours of light per day is appropriate for most setups.

Diet and Feeding

Sterbai Corydoras are omnivorous bottom-feeders with a hearty appetite and a straightforward diet in captivity. In the wild, they forage through sandy substrates for insect larvae, small crustaceans, worms, and organic detritus. In the aquarium, they should be offered a varied diet that includes both high-quality prepared foods and regular supplementation with live or frozen foods.

Sinking pellets or wafers formulated for bottom-feeding catfish should form the staple of the diet. These ensure that food reaches the substrate where the fish feed, rather than being consumed by mid-water tank mates before the corydoras have a chance to eat. Look for products with a high protein content and avoid those that are excessively bulked out with plant-based fillers. Sinking catfish pellets, shrimp wafers, and high-quality micro-granules are all suitable options.

Live and frozen foods are eagerly accepted and should be offered several times per week to promote optimal health, colour, and breeding condition. Bloodworm, tubifex, daphnia, brine shrimp, and chopped blackworm are all excellent choices. Live foods in particular stimulate natural foraging behaviour and are the most effective conditioning food if breeding is desired. Blanched vegetables such as courgette, cucumber, or shelled peas can be offered occasionally as a supplementary food source, though these are not a dietary priority for this primarily carnivorous species.

Feed once or twice daily, offering only as much food as the group can consume within a few minutes. It is a common misconception that corydoras will thrive solely on leftover food that falls from upper-level fish. While they will certainly scavenge uneaten food, they require targeted feeding to ensure adequate nutrition. Evening feeding, when the fish are most active, often yields the best response. Remove any uneaten food after feeding to prevent it from fouling the substrate and degrading water quality.

Behaviour and Temperament

The Sterbai Corydoras is a peaceful, sociable, and endlessly entertaining fish to observe. It is strictly non-aggressive and poses no threat to any tank mate, including the smallest shrimp fry. These fish spend the majority of their time at the very bottom of the tank, methodically working their way across the substrate with their barbels in constant contact with the sand, pausing to sift mouthfuls of substrate and expel it through their gills in search of edible morsels. This foraging behaviour is one of their most charming characteristics and is best appreciated over a fine sand substrate where it can be performed naturally.

Sterbai Corydoras are highly gregarious and should always be maintained in groups. When kept in sufficient numbers — six at a minimum, though more is always better — they exhibit a range of fascinating social behaviours. They will rest together in tight clusters during quiet periods, often stacking on top of one another in amusing poses, and will forage as a coordinated group, sweeping across the tank floor in a loose formation. Solitary or pair-kept specimens tend to be shy, stressed, and significantly less active, often hiding for extended periods and failing to thrive.

The characteristic surface-dashing behaviour, in which a fish shoots rapidly to the water surface, gulps a mouthful of air, and darts back down, is a normal part of corydoras respiratory behaviour and not cause for alarm unless it becomes extremely frequent. This facultative air-breathing is an adaptation to the sometimes oxygen-poor waters of their natural habitat.

Sterbai Corydoras tend to be most active during the early morning and evening hours, with periods of rest during the brightest part of the day. They are generally unperturbed by moderate activity around the tank but may become skittish in very exposed setups with insufficient cover. Providing a well-structured environment with hiding spots and subdued lighting during the day will encourage bolder behaviour and more frequent daytime activity.

Tank Mates

The Sterbai Corydoras is one of the most versatile community fish available, compatible with a very wide range of peaceful to moderately active tropical species. Its preference for warmer water opens up pairing options that are unavailable with many other corydoras species. When selecting tank mates, the primary considerations are avoiding aggressive or predatory fish, choosing species that will not outcompete the corydoras for food at the substrate level, and ensuring that all species share compatible water parameter requirements.

Good tank mates

• Discus — one of the few corydoras species genuinely suited to the warm water that discus require, making them ideal companions for the bottom level of a discus aquarium.
• German Blue Ram — a peaceful dwarf cichlid that shares the Sterbai’s preference for warm, soft water and occupies the lower to mid-water levels without causing conflict.
• Cardinal Tetra — a classic Amazonian schooling fish that thrives in the same warm, soft, acidic conditions and adds a beautiful splash of colour to the mid-water zone.
• Rummy Nose Tetra — another excellent warm-water tetra that shoals tightly in the middle of the tank and coexists peacefully with bottom-dwelling corydoras.
• Ember Tetra — a diminutive, non-competitive schooling fish that occupies the upper and mid-water areas, leaving the substrate entirely to the corydoras.
• Bristlenose Pleco — a peaceful algae-eating catfish that, while also a bottom-dweller, is generally non-aggressive and coexists well with corydoras in suitably sized tanks.
• Kuhli Loach — a gentle, nocturnal bottom-dweller that shares similar substrate and water chemistry preferences without competing aggressively for food.
• Harlequin Rasbora — a calm, mid-water schooling fish that thrives in soft, slightly acidic water and poses no threat to corydoras.
• Cherry Shrimp — a peaceful invertebrate that occupies similar tank zones but is entirely ignored by Sterbai Corydoras, making them safe companions in planted tanks.
• Apistogramma cacatuoides — a generally peaceful dwarf cichlid that can coexist with corydoras provided the tank offers sufficient space and cover for both species.

Fish to avoid

• Oscar — a large, predatory cichlid that will readily consume or injure small catfish and is far too boisterous for a corydoras community.
• Jack Dempsey — an aggressive and territorial cichlid that poses a serious physical threat to peaceful bottom-dwellers.
• Green Terror — a large and belligerent cichlid that will dominate the lower levels of the tank and harass or kill corydoras.
• Tiger Barb — a notorious fin-nipper that can stress and injure slower-moving species, particularly when kept in insufficient numbers.
• Red Tail Catfish — a massive predatory catfish that will consume any fish it can fit in its mouth and is wholly unsuitable for community aquaria.
• Common Pleco — while not aggressive per se, this species grows exceptionally large and produces a heavy bioload that can overwhelm a tank, and its size can inadvertently displace or stress smaller bottom-dwellers.
• African Rift Lake Cichlids — most require hard, alkaline water that is incompatible with the soft, slightly acidic conditions preferred by Sterbai Corydoras, and many are highly territorial.
• Flowerhorn — an extremely aggressive hybrid cichlid that should only be kept alone or with very robust tank mates, never with small, peaceful catfish.

Breeding

Breeding Sterbai Corydoras in the home aquarium is achievable with patience and attention to water conditions, though it is somewhat more challenging than breeding some of the smaller, prolific corydoras species such as Hoplisoma aeneum or Hoplisoma paleatum. Success rates are highest with well-conditioned, mature fish kept in a group that allows natural pair formation.

To condition fish for breeding, increase the proportion of live and frozen foods in the diet over a period of two to four weeks. Bloodworm, blackworm, and brine shrimp are particularly effective conditioning foods. Both males and females should appear plump and active, with females developing a noticeably rounded abdomen when viewed from above, indicating that they are gravid with eggs.

Spawning is typically triggered by a large, cool water change that simulates the onset of the rainy season in their natural habitat. Replace 50–70% of the tank water with slightly cooler, softer water — a drop of two to three degrees Celsius is often sufficient. This can be repeated over successive days if spawning does not occur immediately. A drop in barometric pressure, such as before a storm, is also anecdotally associated with spawning activity in corydoras, though this is difficult to replicate deliberately.

The spawning behaviour follows the classic corydoras T-position, in which the female presses her mouth against the male’s genital area while he releases sperm. The female catches the sperm and uses it to fertilise a small clutch of eggs, which she holds between her pelvic fins. She then deposits the adhesive eggs on a pre-cleaned surface — typically the aquarium glass, broad plant leaves, or the underside of driftwood. This process is repeated numerous times over several hours, with the female depositing eggs in multiple locations around the tank. A healthy spawning can produce 50 to 200 or more eggs.

The eggs are relatively large for corydoras, pale cream or white in colour, and hatch in approximately four to five days at 26 °C. Unfertilised eggs will turn white and develop fungus; these should be removed promptly to prevent the fungus from spreading to viable eggs. Many breeders add a few drops of methylene blue to the hatching container as a prophylactic antifungal measure. If breeding in a community tank, removing the eggs to a separate hatching container with gentle aeration and matching water parameters will significantly improve survival rates, as adult fish and tank mates will readily consume both eggs and fry.

Newly hatched fry are tiny and will subsist on their yolk sacs for the first day or two. Once free-swimming, they can be fed microworms, freshly hatched brine shrimp nauplii, and finely powdered fry food. Maintain impeccable water quality in the rearing tank with frequent small water changes, and avoid strong filtration that could trap the fry. Growth is steady but not rapid, and the young fish will begin to display recognisable adult patterning within a few weeks.

Common Diseases

Sterbai Corydoras are generally robust fish when maintained in clean water with appropriate parameters, but they are susceptible to a number of common freshwater diseases, particularly when stressed by poor conditions or incompatible environments.

Barbel erosion is one of the most frequently encountered issues in captive corydoras and is almost always caused by poor substrate choice or dirty conditions. Keeping these fish on sharp or coarse gravel will gradually wear down and damage their delicate barbels, leaving them vulnerable to secondary bacterial infections. Maintaining a fine, smooth sand substrate and clean tank conditions effectively prevents this problem. If barbel erosion is observed, improving substrate and water quality will usually allow gradual regrowth.

White spot disease (ich), caused by the protozoan parasite Ichthyophthirius multifiliis, can affect Sterbai Corydoras, particularly during periods of stress such as after transport or when water temperatures fluctuate. The classic presentation is small white cysts on the body and fins. Treatment involves gradually raising the temperature to 28–30 °C (which Sterbai tolerate better than most corydoras) and, if necessary, using a half-dose treatment of a suitable ich medication. It is critical to note that corydoras are sensitive to many common aquarium medications, particularly those containing copper or malachite green at full dose. Always use medications at reduced concentrations and monitor fish closely during treatment.

Bacterial infections, including fin rot and skin ulcers, can occur in fish stressed by poor water quality, overcrowding, or aggressive tank mates. These typically present as reddened, frayed, or deteriorating fins and patches of discolouration on the body. Improving water quality is the first and most important step, often resolving mild cases without the need for medication. More advanced infections may require treatment with a broad-spectrum antibacterial product safe for scaleless fish.

Internal parasites can occasionally affect wild-caught specimens or fish that have been fed live foods from contaminated sources. Symptoms may include weight loss despite a good appetite, white or stringy faeces, and lethargy. A course of treatment with an appropriate anti-parasitic medication is usually effective if administered promptly.

Preventative care is always preferable to treatment. Maintaining stable water parameters, performing regular water changes, feeding a varied and nutritious diet, keeping fish in appropriate group sizes, and quarantining new arrivals before adding them to an established tank will collectively minimise the risk of disease.

FAQs

How many Sterbai Corydoras should I keep together?

You should keep a minimum of six Sterbai Corydoras, though groups of eight to twelve or more are ideal. These are highly social fish that rely on the presence of conspecifics for security and the expression of natural behaviours. Solitary or pair-kept specimens are invariably stressed, shy, and less active. In a larger group, you will observe more natural foraging, playful interaction, and the entertaining communal resting behaviour for which corydoras are known.

Can Sterbai Corydoras be kept with discus?

Yes, the Sterbai Corydoras is one of the very best corydoras species for a discus aquarium. Unlike many of its relatives, which prefer slightly cooler conditions, the Sterbai thrives at temperatures of 26–28 °C, which falls comfortably within the range preferred by discus. Both species also favour soft, slightly acidic water. The corydoras will occupy the bottom of the tank without competing for the discus’s food or space, and their peaceful nature ensures no conflict between the species.

What is the best substrate for Sterbai Corydoras?

Fine, smooth sand is the best substrate for Sterbai Corydoras. These fish spend nearly all of their time on the substrate, using their sensitive barbels to sift through it for food. Coarse, sharp, or rough gravel can damage and erode their barbels, leading to pain, infection, and reduced feeding ability. Play sand, pool filter sand, or smooth aquarium sand in a natural colour are all excellent choices. The substrate should be kept clean through regular gravel vacuuming to prevent the accumulation of detritus and harmful bacteria.

Are Sterbai Corydoras the same as Corydoras haraldschultzi?

No, although the two species are frequently confused due to their superficially similar appearance. The key difference lies in their colour pattern. Sterbai Corydoras display white or cream spots on a dark brown to black background, while Hoplisoma haraldschultzi display dark spots on a lighter background — effectively the inverse pattern. Additionally, the Sterbai typically shows more vivid orange colouration on its pectoral and pelvic fins. The two species originate from different river systems and, while care requirements are broadly similar, they are distinct species.

Why do my Sterbai Corydoras keep swimming to the surface?

Occasional dashes to the surface to gulp air are a completely normal behaviour in all corydoras species. They are facultative air-breathers, capable of absorbing oxygen through the lining of the intestine when dissolved oxygen in the water is insufficient. If your fish make this trip a few times an hour, it is nothing to worry about. However, if they are doing it constantly and appear frantic, it may indicate low dissolved oxygen levels in the water. Check that your filter is providing adequate surface agitation, consider adding an airstone, and test your water parameters to rule out any quality issues.

Related Guides

• Bronze Corydoras (Hoplisoma aeneum) Care Guide — a closely related and equally popular corydoras species that shares similar care requirements, useful for comparison if choosing between species.
• Panda Corydoras (Hoplisoma panda) Care Guide — another widely kept corydoras with slightly different temperature preferences, helpful for understanding the diversity of care needs within the group.
• Discus Care Guide — essential reading if you plan to keep Sterbai Corydoras alongside discus, covering the specific water parameters and husbandry that both species share.
• German Blue Ram Care Guide — a frequently recommended warm-water tank mate for the Sterbai, with overlapping care requirements detailed in this companion guide.
• Corydoras Breeding Guide — a comprehensive guide covering spawning techniques, egg care, and fry rearing applicable to the Sterbai and other corydoras species.