The name “Cory Catfish” refers to the genus Corydoras, of which there are over a hundred species. Corydoras are small armored catfish in the family Callichthyidae. Corydoras means “helmet armor” in greek (“cory” = helmet, “doras” = skin/armor). Cory catfish can be found throughout South America, with Corydoras sterbai most commonly found in tributaries in Bolivia and Brazil.
Sterba’s cory catfish are some of the most striking animals in the genus Corydoras. They have white spots on a dark brown base on the face which turns into brown spots on the side of the body and extend into the fins. The pectoral fins of mature catfish take on an orange tint, which is especially attractive.
A small group of 3-6 individuals can be housed in an aquarium as small as 10 gallons, however they are better suited for aquariums 20-30 gallons in size. Corydoras catfish strongly prefer to be in schools and should be maintained in groups of no less than 3-6. Their ideal enclosure will also feature a fine sandy substrate for them to root around in for food with the barbels/whiskers on their snout. Larger gravel may injure these sensitive mouthparts.
Sterba’s cory catfish prefers slightly higher than average temperatures, with an acceptable range of 75-82 degrees fahrenheit. This means a reliable, adjustable heater is a must-have for these fish.
Corydoras sterbai does best in neutral-slightly acidic water. Their ideal pH range is 6.0-7.6. The addition of leaf litter or blackwater extract can naturally lower the pH. However, tank raised individuals are often fairly adaptable and may adjust to a pH as high as 8.0 if properly acclimated.
To maintain a Corydoras aquarium, it is recommended you do weekly water changes of 25-50% and monthly filter maintenance. Monthly maintenance includes rinsing the bio media/sponges in treated tap water (to avoid killing the beneficial bacteria). If you are using chemical media such as carbon, this should be changed out once a month as well. Water changes are best done with a gravel siphon to pull any hidden debris out of the substrate. If using sand, which is best for Cory cats, you want to be careful not to suck up too much of the sand when siphoning, so sometimes stirring the substrate very gently while pinching the line and then releasing the siphon slightly above the sand is best. Whenever water is changed, make sure the clean water going into the aquarium is a similar temperature and to treat it with a dechlorinator if you are using tap water.
Corydoras catfish are known for being highly compatible with many different types of community fish. They are also a schooling fish that should be housed with their own kind or similar species of Corydoras (yes, mixed schools can be achieved). Because Sterbai cories prefer warmer temperatures, they should be housed with only tropical species. Cichlids such as apistos, rams, angelfish, and discus make great tank mates as do peaceful species of tetra, rasbora, or barb.
Sterba’s cory catfish only get to 2.5” as adults, making them great scavengers for mid-sized aquariums (10-40 gallons). In general, most Corydoras stay under 3” as adults.
Corydoras are omnivorous scavengers, who will happily clean up whatever food your other community fish miss. However, they should also be offered their own complete diet. They do really well on gel diets such as Repashy Community Plus. These fish may also respond to sinking wafers and pellets formulated for bottom feeders. They appreciate frozen offerings such as bloodworms and brine shrimp. Cory cats also relish live blackworms and white worms as treats.
Corydoras are somewhat difficult to sex, especially when immature. As they approach breeding size and condition, they can be sexed from above. Typically, a female cory catfish will be much more rounded and plump than a male. Males tend to be skinnier and have more pronounced fins.
Corydoras sterbai breed in groups when triggered to spawn (typically by a cool water change). They are among the easiest of the cory cats to spawn. The best ratio for breeding is 2-3 males for every female. The males will chase the female and form a “T-position” by grasping her barbels with their pectoral fins. Sperm is then thought to be taken up through her mouth and passed through the gut.
The female will lay a few eggs at a time clasped between her pelvic fins. She will swim around frantically, looking for an appropriate place to deposit her eggs. Usually the glass of the aquarium is utilized or the underside of plants. Eggs are tough and can be manually removed with either your fingernails or a razor blade. Eggs can be incubated with methylene blue in a small aquarium or container with an air stone or sponge filter. The eggs will hatch in 3-5 days . The fry will absorb their yolk sac about two days later, at which point they can be fed microworms or live baby brine shrimp.