Minimum Tank Size: 20 Gallons (75 Litres)
Care Level: Easy
Water Conditions: 5.5-7.5 pH and Soft to Medium
Temperature: 72-84 °F (22-29 °C)
Maximum Size: 3 inches (7.5 cm)
The bronze corydoras (Corydoras aeneus), also known as the bronze cory and green corydoras, is a small, tropical catfish that ranks among the most popular catfish kept in home aquariums.. They are native to South America and can found from Argentina in the south, all the way up to Columbia in the north.
They primarily tend to inhabit slow moving rivers and streams, and prefer areas with shallow, muddy water. With that being said, they can also be found in everything from fast flowing rivers, to nearly stagnant pond and marshes.
They are one of only a handful of fish that can thrive in stagnant water, and they do this by utilizing their specialized ability to breath air from the surface of the water. Even in the home aquarium, you will often see them darting to the surface to take a quick gulp of air, and then diving back down to the bottom.
Bronze corydoras stay relatively small in the home aquarium, and the females grow slightly larger than the males. Most females will grow up to 2 3/4 inches (7cm), while the males generally top out at 2 ½ inches (6.5 cm). A well cared for bronze corydoras will easily live for 10 years in a home aquarium, and it’s not unusual for one to live significantly longer.
It’s commonly accepted that the minimum tank size for bronze corydoras is 10 gallons (37 litres), but they only seem to truly thrive when provided with a 20 gallon (75 litre) “long” tank. The width of the tank is more important than the height, as they spend the majority of their time digging and sifting through the substrate for food.
In the wild they combine into large schools with dozens of fish, so they should always be kept in groups of at least five. Even when they are kept in groups of five, they may still exhibit some shyness, and their schooling behavior only really shines when they are kept in groups of at least eight.
When choosing a filter for bronze corydoras, it’s important to remember that they appreciate calm waters, and steps should be taken to ensure that the current is kept to a minimum. You can still use an HOB (hang-on-back) filter on the tank, but the tank shouldn’t be over- filtered.
I would strongly recommend choosing an Aquaclear Power Filter for a bronze corydoras tank. This filter combines excellent filtration with a durable design, and it will keep your tank sparkling clear for years to come. You can also read the Aquarium Tidings Aquaclear Filter Review here.
You also need to provide a suitable substrate for bronze corydoras and any substrate with sharp edges should be avoided. Bronze corydoras spend much of their time sifting through the substrate foraging for food, and their barbels are easily damaged by any sharp surfaces.
Idealy, the substrate should be composed of sand, though soil will also work if you’re willing to deal with the numerous issues that soil brings along with it. If you decide to go the gravel route, make sure to choose a high quality aquarium gravel – preferably one of the numerous ones coated with epoxy.
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Bronze corydoras are omnivores, and mainly feed on small crustaceans, worms, and insects in the wild. This diet should be reproduced as closely as possible in the home aquarium, and this can be done through feeding a high quality flake or pellet food, and live or frozen foods.
Their favorite live foods are bloodworms, blackworms and brine shrimp. They tend to ignore other live foods that remain near the surface of the water and should only be fed live foods that sink to the bottom. Their tastes in frozen foods are similar, and they can be fed brine shrimp, blackworms, bloodworms and daphnia.
If they are kept in fish tanks with other fish, effort needs to be taken to ensure that they are receiving enough food. A common issue is that other fish will eat all of the food, before any of it can sink down the to catfish. This can be remedied through the use of pellets, or feeding flakes and sinking foods at the same time. I recommend using Hikari Sinking Wafers, which is one of the best foods on the market.
Breeding corydoras catfish is not difficult, and in many instances they will breed on their own in a home aquarium. But if you want to trigger breeding, there are certain steps you can take that will increase your chances.
To begin with, try to ensure that you have more males than females in the tank, and a good ratio to aim for is two males for every female. Once the females in the tank begin to plump up with eggs, it’s time for you to attempt to trigger breeding.
The rainy season in the wild always triggers breeding in bronze corydoars, and you can simulate this in the home aquarium through a single, large water change (50%+ of the water). The water that you use should be slightly cooler than the water in the aquarium. If a single, large water change doesn’t work, you should then try small, daily water changes (around 10% of the water) until the fish begin mating.
You can usually tell that mating has started, when the males begin to chase the females. This will usually go on for several days, until the females then start to chase the males around the tank. Shortly after that occurs, you will likely notice several catfish in their breeding position, which is known as the “T-position”. The females mouth will be adjacent to the males mid-section, while the male generally stays at a 90 degree angle to the female.
After they have copulated in this position, the female will deposit her eggs in a place that she has cleaned before hand. Any tank that has been set up for breeding purposes should contain fine leaved aquatic plants, or a breeding mop to provide a place for the females to lay their eggs. If none are provided, they may still deposit the eggs on a flat surface in the tank or the aquarium glass itself.
After the female has laid her eggs, all of the adult bronze corydoras should be removed from the tank. In most cases, the eggs in the tank will hatch in four to five days, and they will continue to hatch for up to 24 hours in some cases.
The newborn fry should be fed infusoria, and then can be moved on to baby brine shrimp, microworms, and powdered flake food or any of the commercially available foods.