- Scientific Name: Corydoras arcuatus
- Synonym: None
- Common Name: Skunk Cory, Arched Cory
- Family: Callichthyidae
- Origin: Brazil, Columbia, Ecuador, Peru
- Adult Size: 2 inches (5 cm)
- Social: Peaceful schooling fish
- Lifespan: 5 years
- Tank Level: Bottom
- Minimum Tank Size: 10 gallons
- Diet: Omnivore
- Breeding: Egglayer
- Care: Easy
- pH: 6.8-7.5
- Hardness: 2 - 25 dGH
- Temperature: 72-79 F (22-26 C)
Corydoras arcuatus originates from the upper Amazon River basin in Brazil, Colombia, Ecuador, and Peru. Although some wild caught fish are available, most Skunk Cories now sold are captive bred on commercial farms.
Like other members of the Cory family, the Skunk Cory is an armored catfish. That means that instead of scales they possess overlapping bony plates, as well as sharp spines on their fins. This ‘armor’ offers them some measure of protection from predatory fish. It also means that owners should exercise care when netting them, as the spines can get caught in the net.
Another trait the Skunk Cory possesses is the ability to supply at least part of their oxygen needs by breathing air directly. They are able to do this by gulping air at the surface of the water. As the air passes through their specialized intestinal tract, oxygen is absorbed into the bloodstream. Should their environment become oxygen deprived, this unique adaptation can make the difference between life and death.
The body of the Skunk Cory is cream-white colored, sometimes showing an attractive yellow-gold sheen. A black stripe begins at the mouth, runs through the eye and arches along the back, thus giving rise to both commons names of Arched Cory and Skunk Cory. This stripe continues to the beginning of the tail where it turns sharply downward. When alarmed or resting, all or part of the stripe may turn so pale it almost disappears. The fins are transparent; however the tail has a smattering of very tiny dark spots. Frequently confused with Corydoras narcissus, the Skunk Cory has a much shorter nose.
The Skunk Cory does best in a planted tank, preferably with driftwood or similar decor that provides hiding places. Open swimming area should also be provided, as well small, smooth surfaced gravel to preserve their sensitive barbels. Sand, which is similar to their native Amazonian habitat, makes a great alternative to standard gravel substrate. Dim lighting as well as blackwater conditions, are ideal for this species. However, very acidic water conditions should be avoided.
Good water conditions are key to the health of the Skunk, as elevated ammonia, nitrites and nitrates are more stressful to this species than other fish. Frequent water changes are important, as well as good filter maintenance. Avoid using aquarium salt in the aquarium, as Skunk Corys are not tolerant of salt. This is true of most scaleless species.
In nature this species lives in large schools, and does not do well alone. Groups of a half dozen or more are recommended. Skunk Cories are quite peaceful, making them suitable for community aquariums made up of other small to medium sizes peaceful species.
Examples of suitable tankmates are other small peaceful Catfish, Dwarf Cichlids, Danios, small Gouramis, Rasboras, and small Tetras. Avoid keeping with large and aggressive species of fish.
Skunk Cories are omnivorous, and will accept a wide range of foods. Because they are primarily a bottom dweller, it is important to include sinking foods in their diet. Live foods, such as bloodworms and brine shrimp are well accepted. If live foods are not available, frozen foods are an acceptable substitution. Sinking pellets are a good staple food for this species.
Corydoras arcuatus is one of the more challenging of the Cory species to spawn. Begin by preparing a breeding tank with a sand bottom and plenty hiding places. Anubis and Java Moss are good plant selections for the breeding tank. Filtration should be robust, as Corys prefer strong currents for spawning. The pH of the water should be close to 7.0, hardness no more than 10 dH and initial water temperature in the range of 72 to 79 F (22-26 C).
Introduce the breeders to the tank, at a ratio of two males per female. Condition the breeders with a variety of live foods, such as brine shrimp, daphnia, mosquito larvae, Tubifex and whiteworms. If live foods are unavailable, frozen foods may be used. Perform a 10 to 15% water chance twice a week to ensure that water quality remains pristine. When performing water changes use water that is two or three degrees cooler than the aquarium water to stimulate breeding.
Females will become noticeably plumper as they fill with eggs, and will begin cleaning possible spawning locations within the tank. Meanwhile, males will also become more active, swimming nervously about the tank. At times they will stop and remain stationary in the water, extending their fins and shaking their entire body. As spawning nears, the males assume a T position in front of the head of the female, grasping her barbels between his pectoral fins and body.
The female cups her pelvic fins to form a basket into which she releases several eggs. It is believed that in this species, the female swallows the sperm and subsequently releases the sperm onto the eggs she is holding. Once fertilized, she places the adhesive eggs on the spots she previously cleaned. It is not unusual for the males to chase the female in an attempt to be chosen to fertilize the next batch of eggs she releases. This process will continue until a hundred or more eggs are laid.
At this point the parents should be removed from the breeding tank, as they will consume the eggs once spawning is complete. Another option is move the eggs to a rearing tank. Place a few drops of methylene blue in the egg tank to prevent the formation of fungus. Some breeders have found that Cherry Shrimp are an excellent means to remove fungus from eggs. They will eat the fungal spores and any diseased eggs, but will leave healthy eggs unharmed. It is important that the tank is well oxygenated, using a sponge or box filter so that fry are not sucked into the filter intake.
In three to five days the eggs will hatch, and will subsist on their egg yolk sack for several days. After that, they will need to be fed freshly hatched brine shrimp. microworms, or commercially prepared fry powders. Frequent water changes are important to maintain good water quality. Many losses at the fry stage are due to improper water conditions.