Corydoras sterbai

Corydoras sterbai is one of the most popular species of Corydoras due to its attractive markings. Sterba’s Cory is distinguishable from other Corydoras species as it has white spots on its head from eyes down to snout. Like many Corydoras species, Sterba’s Cory is a shoaling catfish, and thus should ideally be kept in groups of 5 or more. In the wild it can be found in Bolivia and Brazil and thus, wild caught fish prefer soft, acidic water. However, Sterba’s Cory is a hardy fish and tank bred specimens have adapted to a wider range of water conditions. However, like almost all fish it will not tolerate high levels of nitrates. Unlike some other catfish they are not good algae eaters, but are good at cleaning up leftover food and detritus from the substrate. Coryodras sterbai are relatively small for catfish, growing to a maximum size of only 60 – 65 mm.

The species name of this Corydoras is in honour of Professor Dr. Günther Sterba, professor emeritus of zoology of Leipzig University, member of the Royal Swedish Academy of Sciences. Professor Sterba is a professional ichthyologist who nevertheless produced several very popular books regarded as virtual bibles for fishkeepers over the 70’s and 80’s, translated into English under the titles Freshwater Fishes of the World, Aquarium Care and (with Dick Mills) The Aquarists’ Encyclopedia, despite his degree of isolation at that time by virtue of living in the then German Democratic Republic.

A tank measuring 45 x 30 x 30 cm is big enough for a small group of these. Corydoras sterbai will thrive in a tank set up to replicate an Amazon biotope. This would be very simple to arrange. Use a substrate of river sand and add a few driftwood branches (if you can’t find driftwood of the desired shape, common beech is safe to use if thoroughly dried and stripped of bark) and twisted roots. A few handfuls of dried leaves (again beech can be used, or oak leaves are also suitable) would complete the natural feel. Aquatic plants are not a feature of this species’ natural waters. Allow the wood and leaves to stain the water the colour of weak tea, removing old leaves and replacing them every few weeks so they don’t rot and foul the water. A small net bag filled with aquarium-safe peat can be added to the filter to aid in the simulation of black water conditions. Use fairly dim lighting. Alternatively, it also does well in a more standard, preferably well-planted tank. A good maintenance regime is essential with this species as it’s sensitive to deteriorating water conditions. As with all corys, don’t use undergravel filtration and ensure the substrate is kept scrupulously clean. These cats are sensitive to poorly-maintained or dirty substrates and can lose their barbels if kept in poor conditions.

Species Summary:

Scientific Name: Corydoras sterbai (J. Knaack, 1962)
Common Names: Sterba’s Cory or Sterba’s Corydoras
Family: Callichthyidae
Subfamily: Corydoradinae
Type Locality: Rio Guaporé, Brazil
Origin or Distribution: Bolivia and Brazil
Identification: Corydoras are identified by their twin rows of armour plates along the flanks and by having fewer than 10 dorsal fin rays. They are most commonly confused with the other genera in the sub-family, namely Brochis, Scleromystax and Aspidoras. It is hard to misidentify this species but it can be confused with Corydoras haraldschultzi, although the latter is a long nosed species where C. sterbai is the dome headed form – the easiest way to tell them apart is that the Sterba’s Cory has white spots on its head from eyes down to snout. C. haraldschultzi does not.
Disposition: Peaceful Community Fish
Total Length: 60 – 65 mm
Sexing: Females are more rubust. The male has more of a streamlined body while the female is more rounded when viewed from her side. Easiest to view from the top. While breeding the female will be carrying the eggs with her ventral fins.
Lifespan: 10 – 15 Years
Furniture: Shade provided by overhanging rock work, arching bogwood, tall or floating plants are all that is required. Ideally substrate should be sand, but rounded gravel will suffice.
Spawning Method: Not too difficult, will breed as per any Corydoras species giving a good diet and water conditions, and water changes of a lower temperature to induce spawning. Two males to one female or one pair. Setup could be a 45 X 30 X 30 cm tank with sand or bare bottom with Java Moss, Java Fern and a sponge filter, adding if you like a power filter for extra aeration and circulation of the water all leading to a hopefully successful spawning.
Eggs Incubation: 3 – 5 Days at 24°C
Filtration: Strong
Water Changes: 1/3 Weekly
General Hardness: 1 – 15 dGH
pH: 6.0 – 7.0
Temperatrure Range: 24°C – 28°C
Lighting: Moderate Light
Diet: Live food, frozen and high quality flake foods
Keeping Difficulty: Less Demanding

 

Corydoras sterbai readily accepts a wide variety of prepared and frozen foods. Flake food is a good staple diet (which will only be consumed once it has fallen to the bottom) as are sinking pellets/wafers. They relish live and frozen foods such as bloodworm, daphnia and mosquito larvae, but ideally should only be fed such foods once a week due to the high amount of protein in them. It is often problematic to feed Corydoras in aquaria with fast feeding mid-water fish such as tetras as flake and sinking pellets are consumed by such fish before they have hit the bottom and sometimes, even while lying on the substrate. However, this problem can be overcome by placing pellets and flake on the aquarium substrate in caves or under bogwood, or other such areas which are not regularly frequented by mid-water fish.

The compatibility of Corydoras sterbai is one of their main selling points as with all other Corydoras species as they are very peaceful catfish and can be kept with other peaceful fish. They should not be kept with overly aggressive bottom dwellers, particularly if there is competition over substrate space as there would be in small tanks or tanks with a large amount of «furniture». Ideal companions would be similar sized tetras or particularly, dwarf cichlids. Ideally Corydoras sterbai should be housed with a fine substrate such as sand or gravel in order to avoid doing damage to their delicate barbels. However, large gravel will suffice as long as it is not sharp edged. Their only other requirement is that shade be provided for them, by means of overhanging rock, large leaved plants, arching bogwood and/or caves. Breeding is not too difficult; good diet together with repeated water changes and drops of temperature are usually sufficient. However, raising the fry is not easy due to its high sensitivity.

Reproduction:

Corydoras sterbai is generally considered one of the easiest Corydoras to spawn and a good choice for the beginner. Set up the breeding tank (45 x 30 x 30 cm or similar is a good size), with either a bare bottom, sand or fine gravel substrate. Use air-powered sponge or box-type filtration as fry won’t be sucked into these and provide some clumps of vegetation such as java moss. A temperature of around 24°C and a pH of 6.5 should be fine. Filtering the water through peat is useful, as is the use of RO water. It’s always better to have a higher ratio of males to females when breeding corys and 2 males per female is recommended. Condition the group on a varied diet of live, frozen and dried foods. When the females are visibly full of eggs perform a large (50 – 70%) water change with cooler water, and increase oxygenation and flow in the tank. Repeat this daily until the fish spawn.

It’s worth observing a couple of notes on general cory breeding at this point. Many species are seasonal spawners, breeding during the wet season in their native countries. This occurs at the same time of year as the UK winter, so if summer breeding attempts are failing, it may be worth waiting until winter before trying again. Additionally, it can take several years for certain species to become sexually mature, so be patient. Finally, different tactics may sometimes be required, such as timing of water changes, oxygenation levels etc. It’s also been suggested that the addition of water from a tank containing spawning or just spawned corys (this can be the same or a different species) may induce spawning behaviour in some of the more «difficult» species. It’s likely that this can be attributed to hormones released by the spawning fish acting as a chemical trigger. Basically, if you aren’t having any luck, don’t be afraid of trying different approaches.

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