Callichthyidae, Subfamily Corydoradinae Common Name: Origin and Habitat:
Upper Rio Araguaia basin, Brazil. Burgess and Sands report a second population in the Rio Negro, Brazil. Occurs in faster-flowing streams; Sands observed them in leaf-littered shallow edges of streams with light-brown (tannin) water. Compatibility/Temperament:
Very peaceful bottom fish, similar to the corys which is closely resembles. Only suitable with smaller, non-aggressive tankmates such as characins, small species catfish, dwarf cichlids. Must be in a group, preferably six or more. Aspidoras Diet
A substrate feeder, sinking foods such as tablets and pellets are accepted, and frozen bloodworms or live worms. Size
Attains 1.4 inches. Minimum Tank Suggestion
10 gallon Water parameters for Aspidoras
Soft (hardness up to 12 dGH) acidic (pH 6.0 to 7.2) water, temperature 22-25C/71-77F. Description
The genus Aspidoras
contains some 14 species that all closely resemble the Corydoras
is distinguished internally from Corydoras
by the fontanel (openings) in the top of the skull; Aspidoras
have a dual fontanel, while all Corydoras have a single fontanel. Externally, Aspidoras
are small in size, and except for one species they have a rounded transverse head shape as opposed to the triangularly depressed head of corys; compared to corys, the head length is slightly longer in relation to the body length in most Aspidoras
species. Some authorities feel the two genera should be combined, but to date they are deemed distinct.
The subject species, A. pauciradiatus
, is probably the most commonly available. It differs from the other species in the genus by having only six soft rays in the dorsal fin; all other species have seven. The pattern is also more distinctive compared to the very similar patterning of the other species; this species has a conspicuous dark blotch basally on the dorsal fin.
Given its habitat of faster-flowing streams, it does better in an aquarium with a slight current from the filter. The aquarium should be well-planted with pieces of bogwood, a dark substrate (fine gravel or sand, provided it is smooth-edged) with some open areas, and subdued lighting which can be partly achieved by floating plants; like corys, Aspidoras
do not like bright lighting. This species will swim mid-water to browse wood and plant leaves, as well as foraging the substrate. As with the corys, mature females are rounder when viewed from above.
Like their cory cousins, Aspidoras
are quite sensitive to water parameters and quality, and highly intolerant of salt, chemicals and medications. Signs of stress usually begin with rapid respiration, then lethargy (often just "sitting" on plant leaves, wood or the substrate respirating heavily, sometimes near the surface) and sometimes rolling onto one side. At such signs, a partial water change of at least 50% with a good water conditioner should immediately be made, and appropriate steps taken to remove the cause. Aspidoras
introduced to new aquaria will settle in much better if the tank is established; they do not adjust well to a new aquarium with still-unstable water conditions and fluctuations.
As in Corydoras
, the dorsal and pectoral fins are each preceded by a spine which is actually a hardened and modified ray, thickened and shortened in the Aspidoras
species; the pectoral fin spine can be "locked" into position by the fish; care must be taken when netting the fish not to entangle these spines, which can also give the aquarist a nasty jab. They are believed to be a defense adaptation, to lodge the fish in the throat of a predator.
All species in the genus will periodically and fairly regularly swim quickly to the surface for a gulp of air. The fish swallows the air and blood vessels in the hind gut extract oxygen from the air; it is then expelled through the vent the next time the fish breaks the surface for another gulp of air. This adaptation is believed to have evolved so that the fish can survive in poorly-oxygenated water such as drying pools during the dry season. It is however essential to the fish's well-being that it regularly swallows air. Aspidoras occur in more highly-oxygenated water than most of the corys.
When first described by Weitzman and Nijssen (1970) this species was placed in the Corydoras
genus, and is still sometimes seen in the literature under the name Corydoras pauciradiatus
. Burgess reassigned it to Aspidoras
in 1989. The two populations in the Rio Araguaia and Rio Negro are separated by a considerable distance, and Burgess (1992) noted that the morphological differences are not sufficient to accurately determine if they are separate species or sub-species. Contributing Members
The following members have contributed to this profile: Byron