Sterba's Cory (Corydoras sterbai)

Common Name:

Sterba's Cory.

Scientific Name:

Corydoras sterbai.

Family:

Callichthyidae.

Sub-Family:

Corydoradinae.

Distribution:

Upper Rio Guapore.

Size:

Approx 3inches.

Diet:

In the wild, they eat some algae and lower plants as well as insects, crustaceans, and worms. They can take flakes and pellets in captivity, especially those that are earmarked for Cories. Shrimp pellets are also greedily attacked. They will take Tubifex and bloodworms greedily, whether they are alive or commercially prepared.

Water Temperature:

70 to 77 degrees Fahrenheit (21 to 25 degrees Celsius).

Water Chemistry:

Moderately hard (dH 12-15), clean, clear, current-filled.

pH:

Ideally 6.5-7.0 (They prefer slightly acidic to Neutral water). Like many fish which are tank bred, they can be acclimatized to a ph slightly outside this range if carried out slowly and carefully.

Life Span:

Potentially 10 years but 2-5 is much more common.

Description:

These tiny little catfish can attain lengths of 3 inches at a maximum. They have a silver backdrop with rows of well-defined black spots (which become reticulations as they near the dorsal surface). Their bellies are bronze. Their fins have rows of faded black spots, their pectoral fins have orange spines and their dorsal fin has a yellow-orange spine. Their face is sooty with pale spots on top of it. They are among the "scaleless fishes", so this needs to be considered when adding medication to the tank. They are also able to utilize atmospheric oxygen with their intestines (but this does not mean that water changes may be ignored). The most prominent features of this species, however, are both their barbels and the eyes, which can sometimes be observed in a motion somewhat like a wink.

Behaviour:

They dig in search for food and will bury themselves on occasion.

These are peaceful shoaling fish. While they have been implicated in the deaths of tank mates, it has been said that if a Cory is seen snacking on a tank mate, one can rest assured that the Cories didn't kill it.

They need a shoal of 6+ conspecifics in order to feel comfortable in their surroundings and in order for you to see the range of corydoradine interactions.

Important to note. Cories sense food by smell more often than by sight. This is important for two reasons. For one, they need to have the barbels remain relatively intact, as these are their olfactory sensors. And, secondly, a Cory that won't eat when it is immediately chow time may not know that such is the case. I have seen many a time when a Cory can have pellets dropped almost literally on top of them and not find it until ten minutes later after taking a circuitous route reminiscent of the most convoluted Bil Keane comic.

Cories will dash to the top to take gulps of air, though they should not be doing this on a frequent basis. One of the first signs that a water change is overdue is the Cories taking disproportionate top runs.
They will also feed at the top if they discover that their tank mates do that and pick up on cues that this is the day's method of feeding.

Cories have the ability to segregate themselves into conspecific groups even though humans may not be able to tell them apart.

Sexing:

Females are slightly larger than males and are more rounded.

Minimum recommended tank size:

20-25 gallons for a small shoal.

Breeding:

A lowering of temperature and barometric pressure, when done in conjunction with water changes, may very well induce spawning. Another trick is the feeding of live foods, especially Tubifex and finely-chopped earthworms. Two or three males to one female seems to be the optimal rate for successful spawning.

Males will pursue the females until they show interest. The female(s) will then clean surfaces (mostly plant surfaces and the glass sides of the tank). There is then more courtship -- the male rubs against the female and touches her head with his barbels. Finally, they start the classic "T-position" during vibrations which dislodge some eggs into the basket which the female has made with her ventral fins. They're then fertilized and the female places them throughout the aquarium. There is a quick rest and then the males advance on the females once again. This continues for a few hours (two to three, usually) and the female deposits between 100 to 300 eggs.

The parents do not disturb the eggs or fry if well-fed, but they might be removed after the spawning so that the fry can be reared separately from their parents. The eggs darken over their five to six day incubatory period. Finally the wrigglers emerge and feed on infusoria for a little while. Supplemental feedings may start within the first week and advancement to fry foods for egg-layers should occur at the end of their first week.

Breeding is difficult for the Corydoras ssp. "advanced beginner" as these are among the few cories from cooler alkaline blackwater conditions. Many aquarists who try to induce them to spawn under conditions suitable for C. aeneus are often disappointed by either failure to spawn or high mortality of the fry.

Miscellaneous:

It is truly easier to have success with cories if they are not treated as scavengers but as community inhabitants of their own right.

Like its similar congener, the Mosaic Cory, Sterba's Cory was only described in 1962 by Knaack and in no other instances.

Photo Credit:

Photo supplied courtesy and ^©Ewan Bennet (Ewee the Arab).