Tail-spot Pygmy Cory
Corydoras australe Eigenmann & Ward, 1907
Corydoras: from the Ancient Greek κόρυς (korus), meaning ‘helmet’, and δορά (dora), meaning ‘skin, hide of an animal’, in allusion to the rows of bony plates on the flanks of genus members.
hastatus: from the Latin hastatus, meaning ‘bearing a spear’, presumably in reference to the “arrow-shaped spot” on the caudal peduncle of this species.
According to current knowledge this species has an extensive distribution when compared with most other members of the genus.
While the type locality (see below) is located on the Amazon main channel, between Sanatrém and Manaus in Amazonas state, Brazil, records also exist from elsewhere in Amazonas state (rio Urubu and floodplain lakes in the vicinity of Manaus), plus Pará state further downstream, Pando, Beni, and Santa Cruz departments in northern and eastern Bolivia (ríos Iténez/Guaporé, Yacuma, Itonomas, Piraí, and Orthon watersheds within the larger Madeira river basin), throughout the Río Paraguay system in southern Brazil (Mato Grosso do Sul state), Paraguay and northeastern Argentina (including ríos Pilcomayo, Confuso, Jejuí Guazú, Manduvirá, and Tebicuary), at least as far south as the confluence of the Río Paraguay with the Río Paraná.
Type locality is ‘Villa Bella [= Parintins, 2°38’S, 56°45’W], Amazonas, Brazil’.
Has mostly been collected from marginal channels, backwaters, swamps, floodplain lakes, and smaller tributaries containing shallow, clear-to-turbid water with substrates of mud and clay. Some habitats contain no vegetation while others feature dense growths of submerged grasses, aquatic or floating plants such as Eichhornia or Pistia (see images).
Sympatric species in Paraguay include Serrapinnus kriegi, Aphyocharax nattereri, and Hyphessobrycon elachys (C. hastatus appears to form a mimetic relationship with these species; see ‘Notes’), Hyphessobrycon eques, Gymnocorymbus ternetzi, Aphyocharax rathbuni, Pyrrhulina australis, Moenkhausia intermedia, M. sanctaefilomenae, Otocinclus vittatus, Satanoperca pappaterra, Apistogramma trifasciata, Laetacara dorsigera, Mesonauta festivus, Crenicichla lepidota, and Eigenmannia virescens.
Maximum Standard Length
25 – 32 mm.
Aquarium SizeTop ↑
Minimum base dimensi0ns of 60 ∗ 30 cm are recommended. This species is unsuitable for modern ‘nano’ aquaria.
Ideally use a substrate of fine sand, although rounded gravel is an acceptable alternative provided that it is kept scrupulously clean.
Other décor is largely down to personal choice, but some cover should be provided to give the fish security, ideally in the form of driftwood roots and branches, leaf litter and live vegetation at the water surface.
Temperature: 20 – 26 °C
pH: 6.0 – 7.5
Hardness: 36 – 215 ppm
Corydoras spp. are foraging omnivores, and most will accept sinking dried foods as well as small live and frozen varieties such as chironomid larvae (bloodworm), Tubifex, etc.
C. hastatus is slightly different in that it is partially adapted to forage on pelagic zooplankton (see ‘Notes’) meaning a diet containing plenty of live Daphnia, Artemia, and suchlike is recommended.
Under no circumstances should they be expected to survive on ‘left-overs’ from other inhabitants of the aquarium or relied on to ‘clean’ the aquarium.
Behaviour and CompatibilityTop ↑
Peaceful and gregarious. Should be maintained in a group of at least 4-6 individuals, ideally 10 or more.
Care must be taken when selecting tankmates due to its small adult size; it does not compete well with much larger or more robust species in the confines of an aquarium.
Females tend to grow larger, and sexually mature individuals are noticeably broader and deeper-bodied than males.
Can be bred in a similar fashion to many other Corydoras species.
Use a ratio of two or more males per female if possible, and when the females are visibly full of eggs perform a large (50-70%) water change with soft, cool water, and increase oxygenation and flow in the tank. Repeat this daily until the fish spawn.
Eggs may be deposited on the aquarium glass, among fine-leaved vegetation or within sunken spawning mops, with the latter particularly recommended since they facilitate easy removal of eggs.
Once spawning is complete either adults or eggs should be removed; the latter can usually be rolled gently up the glass with a finger. The new container should contain the same water as the spawning tank and be similarly well-oxygenated.
Most breeders add a few drops of methylene blue, or an alder cone or two at this point in order to prevent the eggs developing fungus.
Incubation is normally 3-4 days and once the fry have fully-absorbed their yolk sacs they are able to accept small live foods such as microworm, Artemia nauplii, etc.
They are not the easiest to raise, requiring excellent water quality, but seem less susceptible to ailments when maintained over a thin layer of sand rather than in a bare arrangement.
In the aquarium trade, C. hastatus is available less frequently than C. pygmaeus and C. habrosus, the other species most commonly referred to as ‘dwarf cory’ or ‘pygmy cory’.
It is frequently confused with C. pygmaeus, but the two can easily be told apart by colour pattern, since in C. hastatus there is a dark, roughly diamond-shaped spot on the caudal peduncle, whereas C. pygmaeus lacks this marking but possesses a dark lateral stripe on the side of the body. C. hastatus also possesses 1 spinous and 7-8 soft dorsal-fin rays, 2 spinous and 5-6 soft anal-fin rays, 22 bony scutes in the upper portion of the body, and 20 in the lower.
A population from northern Paraguay was described as Corydoras australe Eigenmann & Ward 1907, with this name currently a synonym of C. hastatus. The authors could not find a great deal of difference between the two, only stating that C. hastatus from the Amazon basin possess a “jet-black” lateral stripe, whereas the same feature is indistinct in Paraguayan fish.
C. hastatus exhibits slightly different behaviour to the majority of congeners in that it tends to swim in midwater and spends a large proportion of its time away from the substrate. Its morphology exhibits corresponding adaptations towards a pelagic existence with a relatively large eye, a more terminal mouth position, more strongly-forked caudal-fin, and more symmetrical body shape than most other Corydoras species.
This behaviour allows it to form large, mixed-species aggregations with similarly-patterned small characids such as Serrapinnus kriegi, Aphyocharax nattereri, and Hyphessobrycon elachys. The phenomenon of multiple, similarly-coloured species which coexist and school together is relatively common in the genus, although it is typically displayed by sympatric Corydoras species with only a few examples in which such patterns have evolved in other taxa. The reason is thought to be protection from predators in that they feature cryptic or otherwise disruptive details such as stripes, spots, reticulations, or strongly-coloured fin spines. Similarly-patterned species may therefore have evolved to take advantage of foraging in a larger group while simultaneously adapting to exploit contrasting ecological niches. In Corydoras, this is typically expressed via differences in snout length or mouth position, for example.
The genus Corydoras is among the largest catfish groups and currently contains over 150 valid species.
It is included in the family Callichthyidae, of which members are often referred to collectively as ‘armoured’ or ‘mailed’ catfishes group due to the presence of bony plates in place of scales on the body.
Their taxonomy can be confusing, and numerous undescribed species are also thought to exist. Fish of unconfirmed identification entering the aquarium hobby are therefore typically assigned a ‘C’ or ‘CW’ number for purposes of reference and organisation.
They are facultative air breathers and possess a modified, highly vascularised intestine which has evolved to facilitate uptake of atmospheric oxygen and aid survival in oxygen-deprived environments. In the aquarium you’ll occasionally see them rising to the surface to take in gulps of air.
The stiffened pectoral-fin spines are capable of piercing human skin and a ‘sting’ can be very painful indeed, so care should be exercised when handling them.
It is thought that secretions from the axillary glands at the base of each spine may even be mildly toxic or venomous.
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