Corydoras davidsandsi was described in 1987 by Black. The scientific name Corydoras can be broken down into two parts. Cory = helmet and doras = skin. This is a reference to the double row of bony plates that runs down the flank of this genus. They also derive their common name for this group of fish from this armor: armored catfish. They belong to the family Callichthydae which consists of about 9 genera and 190 species.
The ground colour of the Corydoras davidsandsi is light brown. A black stripe runs across its head and eyes. There is a faint orange spot on the gill cover. The flank has no further markings. A second black stripe runs through the dorsal fin over the back to the rear. At the root of the caudal fin, the black stripe splits. This is best seen from above.
The Corydoras davidsandsi is not the only Corydoras species that has a black stripe pattern. In Corydoras adolfoi, Corydoras duplicareus, Corydoras imitator and Corydoras serratus, the black stripe does not split at the tail. In the Corydoras melini the black stripe does split, but this species lacks the orange and has more markings on the flank. In the Corydoras metae, the black stripe across the back, stops just below the dorsal fin, while in the Corydoras davidsandsi it continues into the dorsal fin. Corydoras davidsandsi also has a longer snout than the Corydoras metae.
Once fully grown, the Corydoras davidsandsi can reach a total length of about 7 centimetres. Only then can you tell the difference between the male and the female. The females are somewhat taller, rounder and fuller than the males. They also seem to be built a bit higher than the males.
Like all armored catfish, Corydoras davidsandsi is a bottom dweller. They feel most at ease in a large school of peers. Therefore keep them in a group of at least six pieces.
Many Corydoras species have a venomous self-defense mechanism to avoid being eaten by larger fish. In case of danger, they can spread and lock the spines in their dorsal and pectoral fins. As a result, they get stuck in the mouth or throat of the attacker, so that another fish will not want to swallow a Corydoras.
Even when catching a Corydoras with a net, they regularly hang in the net with these spines. Be careful when loosening, if the spine gets into your skin it can partially break off and remain in the skin. These wounds are painful and often become inflamed.
In addition to the pointy spines, Corydoras can release a toxin into the water when stressed or in danger. When transported in too small a volume of water or too many Corydoras in the small space, this can lead to rapid death among the fish. It is therefore preferable to only transport the Corydoras with other Corydoras and not too much in one bag.
Corydoras’ venom glands are located in the skin between the serrations on the anterior ray of the pectoral and dorsal fins. When attacked by another fish, they lock these fin rays. The skin around these fin rays is damaged and the poison is released. See the attached photo of a catfish from the Doradidae family with similar venom glands.
The first description is made on the basis of a specimen that was caught in the Rio Unini, which is located in the river basin of the Rio Negro. According to this description, this type was caught in white water. However, this entire environment consists of black water. Presumably, the author meant that they were caught near fast-flowing water.
The habitat consists of streams and flooded forests. The water is coloured dark by the tannins in the organic waste, which creates the characteristic “black” water of the Rio Negro basin. The water here is very soft, has a low conductivity and is somewhat acidic.
With their barbels, they fumble across the bottom in search of something edible. Corydoras are omnivores, so they eat both live and vegetable food. As long as you feed them alternately, a Corydoras is not too picky.
If you keep them in a community aquarium, make sure that there is actual food on the bottom, but not so much that food remains. Some aquarists think that Corydoras live on the waste of other fish, but this is not correct.
They can be fed a variety of flake foods, tablets, pellets, and frozen foods such as red, black and white mosquito larvae, tubifex, brine shrimp, Mysis etc.
Because Corydoras davidsandsi lives in groups, they need some floor space to show them their latching behaviour. Think of an aquarium length of about 90 to 100 centimetres.
The barbels are sensitive and are used to search the bottom for food. Preferably use fine sand on the bottom because this will not damage the barbels. The rest of the decoration could include some wood and plants such as Java fern to give the Corydoras some shelter.
The temperature of the water may be between 20 and 28 degrees Celsius. Keep in mind that fish in the wild are never at the same temperature all year round. Keeping the fish continuously at the lowest or highest temperature indicated can shorten their lifespan.
Breeding aquarium and conditioning
The breeding of Corydoras davidsandsi proceeds as with most other Corydoras species. Prepare a breeding tank that is only set up with a layer of sand on the bottom. Give the parents some hiding places in the form of some Java moss. Make sure there is sufficient flow and aeration in the aquarium and direct the flow towards the glass. This will usually be the place where the eggs are laid.
Now add the parent stock in a ratio of 2 males to 1 female.
Food is an important part of conditioning the fish. Feed them meaty food such as black mosquito larvae, tubifex etc. Keep doing this until you see that the females are full of eggs.
As with many other Corydoras species, the trigger for spawning is a large water change of about 50%. Use water that is considerably colder than the aquarium water. The water should be soft and slightly acidic with a pH of 6.5 – 7.0. Repeat this large water change twice a week until the eggs are laid.
In some cases, a 50% water change is not sufficient. In that case, increase the amount of fresh water to about 75% and increase the aeration and flow in the aquarium.
The dominant male chases after a female. Finally, they take the Corydoras characteristic T position. With his pectoral fins, he grabs the female by her barbels. He pushes the female around hard. This is so rough that the barbs of the female can be damaged. After a maximum of 10 seconds, she breaks free from the male. The female then releases an egg, which she catches with her pelvic fins. With the egg clamped between her fins, she looks for a suitable place to stick the egg. This can be on the glass but also in some Java moss.
The first few times the number of eggs is not very large, about 10 to 15 eggs. As the female gets more experience, this number increases to a maximum of about 30 eggs at a time.
Raising the fry
Unfortunately, you cannot leave the eggs with the parents, because then they will be eaten. You can place the parents back in their community aquarium, but most breeders leave the parents in the breeding tank and move the eggs. You can usually carefully roll the eggs over the glass with a finger. The advantage of leaving the parents alone is that they will likely lay eggs again a week later. You should then continue to change with cooler water twice a week.
Place the eggs in an aquarium with the same water as the parents and again ensure sufficient flow and aeration.
Corydoras eggs mold quickly. Remove the moldy eggs to prevent them from igniting the other eggs. If the eggs continue to get moldy, you can add a few drops of methylene blue to prevent molding. Unfortunately, this product is currently only available on prescription in some countries.
The eggs hatch after 3 to 4 days. They then live on their egg yolk for a while. Only when they have eaten their egg yolk can you feed them very fine food such as microworms and liquifry. Once a bit bigger, around two weeks you can start giving finely crushed flake food and freshly hatched brine shrimp.
It is important for the growing up of the young Corydoras davidsandsi that much and often water is changed, up to about 50% per day. Please note that large fluctuations in water values such as temperature and pH should not occur.
Corydoras davidsandsi is a peaceful schooling fish that scrapes together its food on the bottom. They show nice behaviour, especially in a group. They are excellent fish to keep in a South American biotope with not too large or aggressive fish species.
John de Lange
Bijgewerkt op 8 July 2023 door John