Araguaia Corydoras

Quick Summary

The Araguaia Corydoras is a peaceful, bottom-dwelling catfish best suited to aquarists who can provide soft substrate, stable soft-water conditions, and a group of at least six. It rewards attentive keepers with endearing social behaviour and is a solid choice for community tanks once its modest water-quality needs are met.

🐠 Build a tank around this species

In this guide:

• Introduction
• Quick Stats
• Appearance
• Natural Habitat
• Tank Size and Setup
• Water Parameters
• Diet and Feeding
• Tank Mates

Introduction

The Araguaia Corydoras, scientifically described as Hoplisoma araguaiaense, is a relatively uncommon member of the Corydoradinae subfamily that hails from the Rio Araguaia basin in central Brazil. Following the major 2024 taxonomic revision of the Corydoradinae, this species was placed into the genus Hoplisoma rather than the traditional catch-all genus Corydoras, reflecting a more accurate understanding of the evolutionary relationships within this incredibly diverse group of South American catfish.

Like most of its close relatives, the Araguaia Corydoras is a gregarious, bottom-dwelling fish that thrives when kept in groups. It spends much of its time sifting through the substrate in search of food, using the sensitive barbels around its mouth to locate morsels buried in sand or fine gravel. Its calm disposition and manageable adult size make it an excellent addition to a well-planned community aquarium, though it does have specific requirements regarding substrate type, water chemistry, and social grouping that should be understood before purchase.

This species is not as widely available in the hobby as some of the more mainstream corydoradines such as the Bronze or Peppered Cory, but it does appear periodically in specialist shops and through importers dealing in wild-caught Brazilian species. Its relative rarity adds a touch of exclusivity for the fishkeeper who enjoys keeping less common species, and its behaviour and appearance are well worth the effort of sourcing a healthy group.

Appearance

The Araguaia Corydoras possesses the characteristic armoured body shape shared by all corydoradines – a somewhat compressed, wedge-shaped profile with two rows of overlapping bony scutes running along each flank instead of conventional scales. The body is compact and robust, tapering to a forked caudal fin that provides surprisingly agile movement along the substrate. Two pairs of barbels extend from the upper and lower jaw, and these are essential sensory organs that the fish uses to probe the substrate for food particles.

In terms of colouration, this species typically displays a base colour ranging from pale tan to warm beige, overlaid with a pattern of darker brown or olive-grey markings. The precise patterning can vary between individuals, but most specimens show a series of irregular blotches or saddle-like markings along the dorsal surface, with finer spotting or mottling on the flanks. The head usually carries a dark mask or bar running through the eye, a feature common to many Hoplisoma species. The ventral surface is generally paler, often near-white or cream.

The dorsal fin is triangular and held erect when the fish is alert or active. Like all corydoradines, the leading ray of the dorsal and pectoral fins is a stiffened spine that can be locked into position as a defensive mechanism – something to be aware of when netting the fish, as these spines can become entangled in fine mesh. The adipose fin, a small fleshy fin situated between the dorsal and caudal fins, is another hallmark feature of the group and also carries a small spine.

Sexual dimorphism is subtle but discernible in mature specimens. Females tend to be slightly larger and noticeably broader when viewed from above, particularly when carrying eggs. Males are generally a touch more slender and may have slightly more pointed pectoral fins, though this difference is not always easy to spot without direct comparison of several individuals.

Natural Habitat

Hoplisoma araguaiaense is endemic to the Rio Araguaia basin, one of the major river systems in central Brazil. The Araguaia rises on the Brazilian Plateau and flows northward for roughly 2,600 kilometres before merging with the Rio Tocantins, eventually discharging into the Amazon estuary. The river system drains a mosaic of cerrado (tropical savanna), gallery forests, and seasonally flooded grasslands, creating a wide range of aquatic microhabitats.

In its native range, this species is typically found in shallow, slow-moving sections of rivers, tributaries, and seasonally inundated areas where the substrate consists of fine sand, mud, or a mixture of both, often covered by a layer of leaf litter and organic detritus. The water in these habitats tends to be soft and slightly acidic, stained to varying degrees by tannins released from decomposing plant material. Submerged roots, fallen branches, and marginal vegetation provide shelter and shaded areas where these catfish congregate.

Water temperatures in the Rio Araguaia basin fluctuate seasonally, generally ranging from the low twenties during the cooler dry season to the upper twenties or even slightly above during the wet season. The annual flood cycle profoundly influences the ecology of species in this region; rising waters expand available habitat and increase food availability, while the receding dry-season waters concentrate fish into smaller pools and stream channels. This seasonal variation is worth bearing in mind when designing a captive environment, as it informs the range of conditions under which the species thrives.

As with many Brazilian freshwater habitats, the Rio Araguaia faces environmental pressures from agricultural expansion, deforestation, and hydroelectric development. While the Araguaia Corydoras has not been formally assessed by the IUCN, habitat degradation in the region is a concern for many endemic aquatic species. Responsible sourcing from reputable suppliers and, where possible, supporting captive breeding efforts are worthwhile considerations for hobbyists keeping this species.

Tank Size and Setup

A minimum tank size of 80 litres is recommended for a group of six Araguaia Corydoras. Because these fish are obligate social animals that display markedly reduced stress behaviours and more natural activity patterns when kept in groups, keeping fewer than six is inadvisable. For larger groups of eight to twelve – which is ideal – a tank of 100 to 120 litres or more is preferable. The footprint of the aquarium matters more than its height; a long, shallow tank with a generous base area provides the most usable habitat for these bottom-dwelling fish.

Substrate choice is critical. Like all corydoradines, the Araguaia Corydoras feeds by plunging its barbels into the substrate to locate food. Coarse, sharp-edged gravel can abrade and damage these delicate sensory organs, leading to erosion, infection, and reduced feeding ability. Fine, smooth sand – ideally a natural river sand or purpose-made aquarium sand with a grain size below 2 mm – is the only appropriate choice. A sand bed depth of 3 to 5 cm allows the fish to exhibit their natural foraging behaviour comfortably.

Decoration should aim to replicate the shaded, structurally complex habitats these fish occupy in the wild. Driftwood, bogwood, and smooth river stones provide resting spots and visual barriers, while a scattering of dried leaf litter (Indian almond leaves, oak leaves, or similar) not only mimics the natural environment but also releases beneficial tannins into the water. Live plants are compatible with this setup; hardy species such as Anubias, Java Fern, and Cryptocoryne tolerate the low to moderate lighting that suits corydoradines and do not require planting into the substrate (Anubias and Java Fern are typically attached to hardscape). Floating plants can be added to diffuse overhead light, which helps to reduce shyness.

Ensure there are open areas of sand where the group can forage together – a tank that is entirely filled with hardscape and planting will restrict their natural behaviour. A good balance is roughly 40 to 50 per cent open substrate with the remainder occupied by plants, wood, and decor.

A secure lid is advisable. While corydoradines are not habitual jumpers, they are capable of launching themselves out of the water, particularly when startled. Their ability to gulp atmospheric air at the surface means they do occasionally dart upward with some force.

Water Parameters

The Araguaia Corydoras comes from soft, slightly acidic waters and does best when these conditions are approximated in the aquarium. A pH in the range of 6.0 to 7.0 is ideal for long-term maintenance, though the species will generally tolerate values slightly either side of this range provided they remain stable. Sudden swings in pH or hardness are far more harmful than a value that sits slightly outside the theoretical ideal.

Temperature should be maintained between 23 and 28 C. A mid-range target of around 25 to 26 C suits most community setups and keeps the fish active without pushing their metabolism unnecessarily high. Elevated temperatures increase oxygen demand; if keeping the tank at the warmer end of the range, ensure that surface agitation and oxygenation are adequate.

Ammonia and nitrite must always read zero. Corydoradines are sensitive to poor water quality, and even low levels of dissolved nitrogenous waste can cause barbel erosion, gill damage, and susceptibility to bacterial infections. Nitrate should be kept below 20 ppm through regular partial water changes – 25 to 30 per cent weekly is a reliable baseline for most stocking levels.

If your tap water is very hard or alkaline, mixing it with reverse osmosis (RO) water or using a remineralising product designed for soft-water species can help achieve appropriate parameters. Adding botanical materials such as Indian almond leaves, alder cones, or peat filtration can also soften the water naturally while contributing tannins that create a more comfortable environment for the fish.

Filtration and Equipment

Effective biological filtration is non-negotiable for any aquarium housing corydoradines. These fish produce a moderate bioload relative to their size, and a group of six or more in a well-stocked community tank requires a filter capable of processing ammonia and nitrite efficiently. A hang-on-back filter, canister filter, or mature sponge filter – or a combination thereof – will all work well, provided the total turnover rate is in the region of five to eight times the tank volume per hour.

Flow direction and strength deserve consideration. In the wild, the Araguaia Corydoras inhabits gentle to moderate currents, and the aquarium should reflect this. Avoid directing a powerful outlet jet straight at the substrate, which can create a sandstorm effect and make foraging uncomfortable. Instead, angle the outflow along the length of the tank or use a spray bar to distribute flow more evenly. If using a canister filter, an inline diffuser or a lily pipe can help soften the output.

A reliable heater rated appropriately for the tank volume is essential for maintaining stable tropical temperatures. A heater guard is a sensible precaution in any tank housing bottom-dwelling fish, as corydoradines may rest against the heater glass and sustain burns if it is unprotected. Alternatively, an external inline heater connected to a canister filter eliminates this risk entirely.

Lighting should be moderate to subdued. The Araguaia Corydoras, like most corydoradines, is naturally more active in lower light conditions and may become reclusive under intense illumination. If growing live plants that need stronger light, compensate by providing shaded retreats under overhanging hardscape or floating plants.

An air pump driving a sponge filter or airstone can be beneficial, particularly in warmer setups or during summer months when dissolved oxygen levels drop. Corydoradines can supplement their oxygen intake by gulping air at the surface – a behaviour that is normal and not inherently a sign of distress – but frequent, frantic surface gulping can indicate insufficient dissolved oxygen or deteriorating water quality.

Diet and Feeding

The Araguaia Corydoras is an omnivorous bottom feeder with a diet that, in the wild, consists of insect larvae, small crustaceans, worms, detritus, and organic matter sifted from the substrate. In the aquarium, this translates to an easy-to-manage feeding regime provided food reaches the bottom of the tank rather than being consumed by mid-water or surface-dwelling tank mates.

A high-quality sinking pellet or wafer formulated for bottom feeders should form the dietary staple. Look for products with whole aquatic protein sources (such as fish meal or shrimp meal) listed as primary ingredients, and avoid those padded with excessive fillers or artificial colourings. Sinking catfish tablets or micro-pellets that soften on the substrate and can be easily foraged are ideal.

Supplement the staple diet with regular offerings of frozen or live foods. Bloodworm, daphnia, brine shrimp, tubifex, and grindal worms are all eagerly accepted and provide essential protein and fat that dry foods alone may not deliver in sufficient quantity. Frozen foods should be thawed in a small amount of tank water before feeding. Live foods, if available, are an excellent conditioning tool, particularly in the lead-up to breeding attempts.

Blanched vegetables can be offered occasionally for variety – a small slice of courgette, cucumber, or a piece of blanched spinach anchored to the substrate with a fork or clip will often attract the attention of the group. Remove any uneaten vegetable matter within 12 to 24 hours to prevent it from fouling the water.

Feed once or twice daily, offering only as much food as the group can consume within a few minutes. Overfeeding is a common cause of water quality problems in community tanks, and leftover food decomposing on the substrate is particularly harmful in setups housing barbel-sensitive species like corydoradines. If you notice food consistently remaining uneaten, reduce the portion size.

A common misconception is that corydoradines will subsist on leftovers from other fish and act as a “clean-up crew.” While they do scavenge, they have genuine nutritional needs that must be met with targeted feeding. Relying on scraps alone will result in malnourished, short-lived fish.

Behaviour and Temperament

The Araguaia Corydoras is a peaceful, social species that exhibits classic corydoradine behaviour patterns. It is most active during dawn and dusk, though in a dimly lit or well-planted aquarium it will forage throughout the day. Groups often move in loose shoals across the substrate, pausing to probe the sand with their barbels in a distinctive head-down posture that is one of the most endearing aspects of keeping any corydoradine.

Social grouping is essential to the wellbeing of this species. A minimum group of six is strongly recommended, and groups of eight to twelve produce noticeably more confident, active fish. Solitary or pair-kept corydoradines frequently become shy, inactive, and stressed, spending most of their time hidden. In adequate groups, individuals are bolder and display a wider repertoire of natural behaviours, including synchronised foraging, playful chasing, and the characteristic “winking” motion where one eye is briefly rotated downward.

Periodic dashes to the surface to gulp atmospheric air are entirely normal. Corydoradines possess a modified intestinal lining that allows them to extract oxygen from swallowed air – an adaptation to the low-oxygen conditions of their native habitats. This behaviour should not be confused with distress, although a marked increase in frequency can indicate low dissolved oxygen or deteriorating water quality.

The Araguaia Corydoras shows no aggression toward tank mates and is an entirely inoffensive community citizen. It will not compete aggressively for food, which means keepers must ensure that sinking foods reach the substrate before being intercepted. The species is not territorial and does not defend a fixed home area, though groups will often return to favoured resting spots – typically beneath overhanging wood or in plant-shaded areas.

Tank Mates

The Araguaia Corydoras is compatible with a wide range of peaceful community fish. The key considerations when selecting tank mates are temperament, size, and feeding habits. Avoid species that are aggressive, territorial, or large enough to view the corydoradines as food. Equally, avoid boisterous bottom-dwelling species that might outcompete them for food or harass them. Fish that share a preference for soft, slightly acidic water make the most harmonious companions.

Good tank mates

• Cardinal Tetra – A classic soft-water companion that occupies the mid-water column and poses no threat to bottom dwellers.
• Rummy-nose Tetra – Peaceful shoaling species from similar Brazilian river systems that thrives in the same water chemistry.
• Ember Tetra – A tiny, non-competitive tetra ideal for smaller community setups alongside corydoradines.
• Harlequin Rasbora – Calm mid-water dweller that appreciates soft, slightly acidic conditions.
• Otocinclus – A fellow peaceful bottom-dweller and algae grazer that coexists without competition for the same food sources.
• Kuhli Loach – Another gentle substrate-level fish that shares similar habitat preferences and feeding habits.
• Honey Gourami – A placid surface-to-mid-water species that adds colour without creating conflict at the bottom of the tank.
• Pencilfish – Small, unobtrusive upper-water fish that complement corydoradines well in a South American biotope theme.

Fish to avoid

• Oscar – Far too large and predatory; would view the Araguaia Corydoras as food.
• Red-tail Catfish – A massive predatory catfish wholly unsuitable for community aquaria with small corydoradines.
• Jack Dempsey – Aggressive cichlid that would bully and potentially injure or kill small bottom dwellers.
• Tiger Barb – Notorious fin nipper that can harass slower-moving species, causing chronic stress.
• Common Pleco – Grows extremely large and can become territorial at the substrate level, outcompeting corydoradines for space and food.
• African Cichlids – Require hard, alkaline water incompatible with the Araguaia Corydoras, and most species are too aggressive.

Breeding

Breeding the Araguaia Corydoras in captivity follows the general pattern seen across the corydoradine group, though detailed captive breeding reports for this particular species are less common than for staple species like Hoplisoma aeneum or Hoplisoma paleatum. With patience and appropriate conditioning, successful spawning is achievable for a moderately experienced hobbyist.

Begin by ensuring you have a group of at least six individuals, ideally with a ratio of two males to every female. This provides adequate competition among males, which appears to stimulate spawning behaviour. Condition the group heavily for two to three weeks with protein-rich live or frozen foods such as bloodworm, daphnia, and grindal worms.

Spawning in corydoradines is often triggered by environmental cues that mimic the onset of the rainy season. A large, cool water change – replacing 30 to 50 per cent of the tank volume with water 2 to 3 C cooler than the current temperature – combined with a drop in barometric pressure can stimulate breeding activity. Some breeders also report success by slightly lowering the water level and then refilling it over a few hours. Performing these water changes in the evening can be effective, as spawning activity frequently begins in the early morning hours.

The spawning process follows the distinctive “T-position” courtship unique to corydoradines. The male presents himself broadside to the female, who cups one or two eggs in a basket formed by her pelvic fins. She then swims away to deposit the adhesive eggs on a chosen surface – typically the aquarium glass, plant leaves, or smooth pieces of hardscape. This cycle repeats numerous times over several hours, with a single spawning event potentially producing 50 to 150 eggs depending on the size and condition of the female.

Eggs are susceptible to fungal attack, particularly in stagnant water. Removing the eggs to a separate hatching container with gentle aeration and a few drops of methylene blue can significantly improve hatch rates. Alternatively, if breeding in a dedicated tank, remove the adults after spawning, as they will readily consume their own eggs. Eggs typically hatch within three to five days at 25 to 26 C, and the fry become free-swimming a day or two after that, once the yolk sac is absorbed.

Newly free-swimming fry are tiny and require appropriately sized first foods. Infusoria, commercially available liquid fry food, or finely powdered spirulina can sustain them for the first few days, after which they can be transitioned to freshly hatched brine shrimp nauplii – widely considered the gold standard first food for corydoradine fry. Maintain impeccable water quality in the fry tank with gentle sponge filtration and frequent small water changes, taking care to match temperature and chemistry.

Common Diseases

The Araguaia Corydoras is not unusually disease-prone, but like all corydoradines it is sensitive to certain environmental stressors and can be vulnerable to a handful of common aquarium ailments if conditions are suboptimal.

Barbel erosion is one of the most frequently encountered problems in corydoradine-keeping and is almost always caused by inappropriate substrate or poor water quality. Rough gravel abrades the barbels over time, creating entry points for bacterial infection. Sustained exposure to elevated nitrate, ammonia, or nitrite levels accelerates erosion. The condition is easily prevented by using fine sand and maintaining clean water, and early-stage erosion can be reversed simply by correcting these environmental factors.

White spot disease (Ichthyophthirius multifiliis), commonly called ich, presents as small white cysts on the body and fins. It is usually introduced by new, unquarantined additions to the tank. Treatment should be approached cautiously, as corydoradines are scaleless and more sensitive to certain medications. Half-dose treatments of malachite green and formalin-based remedies are commonly recommended; always follow product instructions for scaleless fish. Raising the temperature to 28-30 C while increasing aeration can also accelerate the parasite’s life cycle and improve treatment outcomes.

Bacterial infections, including fin rot and body sores, can occur when fish are stressed, injured, or kept in substandard water. These typically manifest as reddened patches, fraying fins, or ulcerous lesions. Antibacterial treatments are available, but prevention through good husbandry is far more effective than cure. Quarantining new fish for at least two weeks before introducing them to an established tank is a sensible precaution.

Internal parasites can affect wild-caught specimens. Signs include weight loss despite a healthy appetite, white, stringy faeces, and general lethargy. Antiparasitic foods or treatments containing praziquantel or levamisole are commonly used. If you suspect internal parasites, treat the entire group, as transmission within a shared environment is likely.

Stress is the underlying factor in most corydoradine health problems. Keeping the Araguaia Corydoras in appropriate group sizes, on soft substrate, in clean water, and with compatible tank mates goes a very long way toward preventing disease in the first place.

FAQs

How many Araguaia Corydoras should I keep together?

A minimum of six is recommended, but groups of eight to twelve are preferable. Corydoradines are strongly social, and larger groups produce more confident, active fish with reduced stress levels. Keeping fewer than six often results in shy, hidden fish that fail to thrive.

Can I keep Araguaia Corydoras on gravel?

No. Coarse or sharp gravel will damage their delicate barbels over time, leading to erosion and infection. Fine, smooth sand is the only suitable substrate for this species and for all corydoradines. If your existing tank has gravel, consider either replacing it entirely with sand or creating a large sand-bottomed section specifically for the corydoradines.

Do Araguaia Corydoras need a heater?

Yes. This is a tropical species requiring stable temperatures between 23 and 28 C. In most temperate climates, an aquarium heater is necessary to maintain these temperatures year-round. Even in warmer regions, a heater provides stability and prevents overnight temperature drops that could stress the fish.

Why does my Araguaia Corydoras keep darting to the surface?

Occasional dashes to the surface to gulp air are entirely normal. Corydoradines possess a supplementary method of respiration that allows them to absorb oxygen through a modified section of their intestine. However, if this behaviour becomes very frequent or frantic, it can indicate low dissolved oxygen levels or deteriorating water quality, and you should test your water parameters promptly.

Is the Araguaia Corydoras the same as Corydoras araguaiaensis?

Yes, it is the same species. Following the 2024 taxonomic revision of the Corydoradinae, many species previously placed in the genus Corydoras were reassigned to other genera, including Hoplisoma. The species previously known as Corydoras araguaiaensis is now formally classified as Hoplisoma araguaiaense. Both names refer to the same fish, and you may encounter either name in older literature or trade lists.

Related Guides

• Bronze Corydoras – The most widely kept corydoradine, sharing almost identical care requirements and serving as an excellent reference point for beginners to the group.
• Peppered Corydoras – Another hardy, commonly available Hoplisoma species with overlapping husbandry needs and similar behaviour.
• Sterbai Corydoras – A popular warm-water corydoradine that thrives in the same temperature range and makes a striking visual companion in a South American community.
• Otocinclus – A peaceful algae-eating catfish that pairs well with corydoradines in soft-water setups and shares many of the same tank requirements.
• Cardinal Tetra – An iconic soft-water tetra from Brazil that is one of the most natural and compatible mid-water companions for Araguaia Corydoras.