Corydoras catfish are one of the most commonly kept community fish because of their gregarious nature, diminutive size, and useful cleaning skills. Therefore, it is no surprise that some fish keepers wonder if they can share the benefits in their Apistogramma tanks.
But, like many other tank mates of Apistogramma, the question of whether or not it’s a good idea to keep Corydoras with them can be somewhat controversial.
Can Apistogramma be kept with Corys Catfish?
The short answer is yes, Apistogramma and Corydoras can live together in the same tank. It is best to only keep them in roomy community tanks with a large footprint so that they can each find their own territories.
For small- to medium-sized tanks, especially in the commonly used Apistogramma aquarium size of 20-gallon tanks, it can be problematic to have these two bottom-dwelling species together.
What Makes Corydoras a Bad Tank Mate for Apistogramma?
While they can coexist in the same tank, there are at least five unavoidable reasons why Corydoras may not make a good tank mate for Apistogramma:
Typically, Apistogramma are Aggressive
No matter how big or small they are, cichlids are territorial and can be aggressive at times; Apistogramma dwarf cichlids are no exception. Even the most “peaceful” Apistogramma borellii can be a little temperamental, even aggressive, if they have to compete for territory with another fish, not to mention those polygamous species from the agassizii lineage.
The problems could be more serious during the spawning season or in smaller tanks with only one hiding spot (cave or plant). The Apistos will relentlessly chase any fish away from the bottom space they have already claimed, and the Corydoras won’t stand a chance.
To keep both fish feeling safe and happy, consider getting a bigger aquarium and then getting started in aquascaping to break up the bottom into separate dwelling areas. Remember that the aquarium’s length is more important than its width.
If you plan to introduce a group of Corys into an established Apistogramma tank, the first and most important thing is rearranging the décor. This alters the Apistos’ territories and can settle things down.
They May Compete or Fight for Food
Corydoras are omnivorous species in the wild, mainly feeding on inverts, worms, and plant matter. In the home aquarium, these bottom scavengers feed on the leftover food that sinks to the bottom of the tank.
Apistogramma are also bottom feeders, but as carnivores, they require higher levels of usable protein. To properly feed them, you must provide sinking pellets specifically developed for carnivorous fish. Some wild-caught specimens are picky eaters and may not bother with prepared flakes and pellets.
Apistogramma and Corydoras appreciate a meal of live food, such as newly hatched brine shrimp, daphnia, and white mosquito larvae. On the one hand, that means the competition for food could be an issue, and the timid Corys may not get their share. On the other hand, be prepared to invest a large amount of time and money to meet their nutritional requirements.
They Prefer Different Water Conditions
Corydoras are known for their adaptability; they are undemanding and can tolerate a range of water conditions. However, they do prefer acidic to neutral pH, and soft to slightly hard water.
It’s worth noting that the most popular and readily available Corydoras tend to thrive in “colder” water temperatures below 79°F (26°C) compared to Apistogrammas. The Sterbai Cory (Corydoras sterbai) is often beloved by Apistogramma enthusiasts because it is one of the few species that prefer warmer water, i.e., up to 82°F (28°C).
Apistogramma mostly inhabit slow-moving rivers and streams in forested areas. Their native environment is typically acidic and soft. Some species were collected from tributaries, creeks, and pools of blackwater rivers, including the Rio Negro, Rio Uatumã, and Rio Madeira. Quite often, these waters are characterized by no detectable hardness.
This is all to say you cannot have your cake and eat it too. Keeping Corydoras with Apistogramma in the same tank is ultimately going to sacrifice their optimal water conditions in favor of one or the other.
Corydoras: The Avid Egg Eaters
As mentioned, Corys are omnivorous and opportunistic eaters, which include Apistos’ eggs. Unlike most catfishes and plecos, they are diurnal species, but they are more active at dawn and dusk when they can take advantage of Apistos’ reproduction.
During the breeding season, Cory catfish may enter the spawning cave of Apistogramma cichlids and steal their eggs for a tasty snack. The female Apistogramma is fiercely protective of her eggs and will chase away intruders, sometimes even attacking their eyes.
If you intend to breed Apistogramma cichlids or want to avoid the risk of losing your cory catfish’s eyes, do not keep them together in a breeding tank. Alternatively, you can remove the Corys until the fry become free-swimming.
Corys Are Exceedingly Unintelligent
Did you know that tetras and Corydoras catfish are considered to be at the bottom rung of the evolutionary ladder when it comes to intelligence? It is true.
In the world of fish keeping, what this means is that they will continue to swim back and forth even if they are constantly harassed by an aggressive Apistogramma. For this reason, these tough and stupid fish have a good chance of entering the Apistogramma’s territory and eating their eggs.
At the end of the day, keeping Apistogramma with Corydoras may not be a good idea; however, it really depends on your goals and expectations. If breeding is not paramount, and you are prepared for some bumps in the road, then go ahead and explore the possibilities.