The bronze corydoras, also known as a bronze cory or a green cory, is a small, tropical freshwater catfish that ranks among the most popular catfish kept in home freshwater aquariums. These fish are easy to care for and hardy, but they are somewhat shy.
Common Names: Bronze cory, green cory
Scientific Name: Corydoras aeneus
Adult Size: 2.5 inches
Life Expectancy: 5 to 10 years
|Origin||Argentina, Colombia, Venezuela|
|Minimum Tank Size||10 gallon|
|pH||6.0 to 8.0|
|Hardness||5 to 19 dGH|
|Temperature||72 to 79 F (22 to 26 C)|
Origin and Distribution
These fish are found in South America from Colombia and Trinidad in the north as far south as the Río de la Plata drainage at the border of Uruguay and Argentina. Bronze corys mostly inhabit slow-moving rivers and streams and prefer areas with shallow, muddy water, however, they have also been found in fast-flowing rivers.
With a special ability to breathe air from the surface of the water, cory catfish are one of the few fish that can thrive in stagnant water. In the home aquarium, you will often see them darting to the surface to take a quick gulp of air and then dive back down to the bottom.
Colors and Markings
Small, active, and peaceful, the bronze cory is just a color variation of the same species known as the green cory. In addition to color variations of green, bronze, albino, and even black, this species is one of many fish that is sometimes injected with dye to enhance its color. Do not purchase any fish specimens that are suspected of being color-dyed as this causes long-term health problems for the fish. It is also wise to avoid any that have damaged barbels, or those having a sunken belly, which indicates inadequate feeding and susceptibility to disease.
Like all corydoras, this species is armored with overlapping scales known as plates or scutes. Their fins possess a leading spine, which can be locked in place to make it difficult for larger fish to swallow them. This spine can also make netting them difficult, and care should be taken when doing so. In the home aquarium, corys are prized for being charmingly expressive.
Bronze corys are a schooling fish. Keep them in groups of at least five. Cory catfish tankmates may include most community tank species as long as they are non-aggressive and friendly in nature. Otocinclus catfish, tetras, swordtails, and other corys can be a good fit. Avoid putting corys in the same tank with oscars, Texas cichlids, or Jack Dempseys. These species can injure corys or may try to eat them.
Bronze Corydoras Habitat and Care
Bronze corys tolerate a wide variety of water conditions. However, they prefer acid to neutral pH, soft to slightly hard water, and temperatures in the middle 70s. They are not tolerant of salt and should always be moved if the tank is going to treated using salt.
All corys like to dig in the substrate in search of food. To avoid irritation to their barbels, use small, smooth-edged gravel or sand as the substrate. They tend to be shy and should be provided with hiding places (preferably of wood or stone), as well as floating plants to subdue the lighting. They prefer low water levels similar to the shallow waters near the banks of the Amazon tributaries that are their native habitat.
Bronze Corydoras Diet and Feeding
In the wild, corys mainly feed on small crustaceans, worms, and insects. Bronze corys are omnivorous and will accept everything from flake to frozen foods. To maintain their good health, a variety of foods should be offered, including their favorite live foods: bloodworms, blackworms, daphnia, and brine shrimp.
Corys tend to ignore live foods that remain near the surface of the water. They are bottom feeders, which can prove to be a problem; other fish may consume most of the food before it reaches the bottom. Owners should use tongs to place foods lower and then closely observe at feeding time to ensure the corys are getting a sufficient amount of food.
It can be tough to tell the difference between a female and male bronze corydoras. Males tend to be smaller and more slender than females, particularly when viewed from the top. A female will be larger due to her more rounded abdominal area.
Breeding the Bronze Corydoras
Spawning bronze corys is relatively easy. Purchasing a half dozen or more young specimens at the same time will ensure having at least one or two breeding pairs. Here's the timeline of what will generally need to be done before, during, and after breeding:
- Feeding: Before breeding, the fish should be conditioned with high-quality flake foods, sinking pellets, fresh or frozen bloodworms, and brine shrimp.
- Inducing spawning: Water should be slightly acidic. Rainwater is often used to lower the pH in the breeding tank, however, care should be taken to ensure that the rainwater is not runoff water that may be contaminated with toxins. A large water change (up to 50 percent) with water that is several degrees cooler than the breeding tank, will often trigger spawning. If you are having difficulties inducing spawning, try simulating actual rain by slowly adding water to the tank using a sprinkler.
- Courting: Normally shy, this catfish becomes very active during courtship. Males will pursue females throughout the aquarium at a breakneck pace, stopping to rub their bodies and barbels against the female whenever the opportunity arises.
- Egg-laying sites: Once the female consents, it will search for suitable egg-laying sites and begin cleaning several suitable locations. As the courtship progresses, roles eventually reverse, and the female begins pursuing the male.
- Spawning: The actual spawning begins in earnest when the pair assumes the classic "T" position. This position triggers the release of sperm as well as one to 10 eggs, which the female will grasp with her pelvic fins.
- Depositing eggs: Once fertilized, the female will deposit the eggs at the site she has previously cleaned. The eggs are sticky and will adhere firmly to the nesting site. Shortly after that, the pair will spawn again, depositing a few more eggs each time. This process continues until the female has released all of the eggs, which can number as many as 100 to 200. Spawning may continue over a period of several days.
- Moving the eggs: Once spawning is complete, the adults should be removed, or the eggs should be moved to another tank where the fry can be reared. If moving the eggs, wait 24 hours before moving them. Eggs are initially translucent but will darken as they develop.
- Hatching: In approximately four to five days the eggs will hatch, although that may vary based on the environment. After they hatch, the fry will live on the yolk sac for another three to four days.
- Feeding fry: Initially, they may be fed infusoria or very fine powdered fry food. You can gradually feed freshly hatched brine shrimp and eventually adult foods.
- Changing water: Frequent water changes (10 percent daily or every other day) are critical during this growing period.
More Pet Fish Species and Further Research
If bronze corys appeal to you and you are interested in some compatible fish for your aquarium, read up on:
- Panda corydoras Species Profile
- Pepper corydoras Species Profile
- Three stripe corydoras Species Profile
Check out additional fish species profiles for more information on other freshwater fish.
How Ornamental Fishes Get Their Color. University of Florida IFAS Extension.