Do Cory Catfish Like Strong Water Current?

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Sometimes, your Cory Catfish might act weird for no reason. You might have noticed strange behaviors like hovering over air stones and swimming against filter outputs and powerheads.

It’s unusual for most fish species to do these things unless there’s something off with the water quality.

Typically, fish hang out around the air stone or filter when there’s an ammonia spike or the water oxygen, pH, and temperature are off. So, why do Corydoras do this even when the water quality is fine?

Simply put, Cory Catfish just like a stronger water current. Swimming against the current is how they play in the tank.

The air stone, powerhead, and filter provide the perfect opportunity for Corys to expend energy and keep themselves entertained.

So, next time you see your Catfish swimming against the flow, know that your fish are just doing their thing. It might even be a good thing to bump up the flow in the tank. Your Corys will thank you.

But how much is too much current, and how do you find the sweet spot for your fish? Keep reading to find out!

Why do Corydoras Like a Strong Water Current?

In short, Corydoras like strong water currents because this is the healthiest and most natural environment for them.

In the wild, Cory Catfish occur in rivers and streams where they get continuous water movement and strong currents. These environmental pressures have made Corys adapt their behavior and swimming style.

When in the aquarium, Corys seek the same stimuli they’re accustomed to in the wild. Even if your fish are captive-bred, this behavior is innate to this species.

Mimicking their natural environment in captivity encourages Corydoras to display their natural behaviors, providing behavioral enrichment.

Swimming against the current is one of these natural behaviors. The strong current keeps them active and entertained, contributing to long-term health and well-being.

Besides physical and psychological benefits, a strong water current also encourages breeding behavior. Corydoras’ breeding season in the wild starts after periods of heavy rainfall when the river’s water current is at its peak.

How do You Know if the Current is Too Strong for Corys?

All Cory Catfish species enjoy water currents in one form or another. Some love fast water flow, like the Sixray Cory, Flagtail Cory, and Panda Cory.

Other species, like the Salt and Pepper Catfish or the Sterba’s Cory, prefer gentler water movement.

So, how much is too much current differs between species. But there are a few general indications that you’re overdoing it.

You might want to tone down the flow rate if:

– The fish can’t rest comfortably on the substrate

Although Corys love keeping active, they still need quiet areas to rest. These bottom-dwelling fish spend quite a bit of time lying on the substrate.

Cory catfish normally spend 5-10 minutes napping multiple times a day.

You’ll know the current is too strong when your fish can’t comfortably rest in one spot. When the fish stop swimming and the water flow sweeps them away, that signifies too much flow.

Your fish should have some lower-flow areas in the tank where they can hover in place effortlessly.

– The fish can’t float at the water’s surface

Cory Catfish have a special labyrinth organ that allows them to get oxygen straight from the air. Thus, it’s normal for Corys to swim to the surface and gasp for fresh air occasionally.

Normally, Corys should manage to float upright and maintain their posture at the surface.

If water waves submerge the fish or the flow sweeps them aside, this is an indication that the current is too strong.

– The fish have problems feeding

Corys are bottom feeders. They search for sinking foods throughout the substrate. If the current in your tank is too strong, the food might take too long to sink.

Alternatively, all the food could end up at one end of the aquarium. If that’s the case, your catfish will have difficulty foraging for goodies.

Can Strong Water Flow Cause Stress to Corys?

Unfortunately, yes! Even if Corys naturally enjoy the current, they can get too much of a good thing. Your fish still need quiet areas where they can sleep, hide, or eat.

Excessive water flow prevents them from doing these activities, causing stress in many ways.

Strong water flow can interfere with your Corydoras’ rest and feeding, causing lethargy and undernourishment.

Besides, having to always swim against the flow becomes exhausting and stressful in itself. Even the most energetic fish get tired at some point.

Also, remember that not all Cory catfish enjoy the same flow rate. On average, Corys tolerate more water movement than other fish. Most Corys thrive in strong currents. But others prefer slower water movement.

If your aquarium output is too strong for your Cory species, this will be stressful for the fish.

Always research and provide suitable water parameters according to your fish’s care sheet.

Do Corys Like Slow-Moving Water?

The ideal water flow rate depends on what Corys you have. It’s best to adapt your aquarium to your fish’s unique requirements, and there’s a lot of variation between different catfish species.

Usually, Corydoras prefer more water movement than other fish. But most Corydoras will either like or tolerate slow-moving water.

Corydoras from environments with shallow, slow-moving waters will appreciate an aquarium with a lower flow. But even active, fast-swimming Corys can adapt to these conditions without issues.

When in doubt, going lower is better, as it reduces the risk of stress in slow-swimming fish. As long as the aquarium isn’t completely stagnant, your Corydoras will be alright.

Try decreasing your filter GPH output or putting a pre-filter sponge over the intake pipe. See how your fish react to the reduced water movement.

Other Fish that Thrive in Fast-Moving Water

Corydoras aren’t the only speedy fish out there. If you want to create a community tank around your catfish, you have plenty of tankmates to choose from.

Below is a list of compatible fish with similar body sizes and water parameters. And, of course, these fish all love going against the flow!

1. Danios

  • Size: Up to 2.5 inches
  • Care level: Easy
  • Temperament: Peaceful
  • Water parameters: 65–80°F, 6.5–8.0 pH, 5–19 dGH
  • Tank space: 10 gallons

There are 27 species and multiple morphs and colors to choose from. This small fish comes in green, pink, yellow, red, purple, blue, orange, black, and even neon colors!

The best part is that you’ll only need 10 gallons for a shoal of six Danios. This is a great community fish for small or well-stocked aquariums!

2. Hillstream and Yoyo Loaches

  • Size: 3-6 inches
  • Care level: Moderate
  • Temperament: Peaceful
  • Water parameters: 68–78°F, 6.0–8.0 pH, 3–10 dGH
  • Tank space: 10 gallons

Both of these species are friendly and highly active. Like Corydoras, these fish are bottom-dwellers and feeders, making a good addition to your cleaning crew.

Hillstream Loaches, in particular, have an interesting, whimsical look. Their wide pectoral fins give them a flattened appearance.

Combined with the complex lace pattern on its body, this fish is a real attention grabber!

3. Rubber Lip Plecos

  • Size: Up to 7 inches
  • Care level: Easy
  • Temperament: Peaceful
  • Water parameters: 72-80°F, 6.5-8.0 pH, 8-12 dGH
  • Tank space: 30 gallons

This fish has a flattened greyish-brown body covered in dark spots. Rubber Lip Plecos can grow considerably, at least compared to Corys.

Luckily, this fish doesn’t hunt for food, so it won’t eat its tank mates. Plecos are scavengers and bottom-feeders, so they’ll eat leftovers and rotten foods, not your live fish.

4. Siamese Algae Eaters

  • Size: Up to 6 inches
  • Care level: Easy
  • Temperament: Peaceful
  • Water parameters: 75-79°F, 6.5-7.5 pH, 5-20 dGH
  • Tank space: 20 gallons

This species has a light grey body with a dark horizontal stripe running from mouth to tail. As its name suggests, this fish is big on eating algae.

Besides making excellent friendly community fish, Siamese Algae Eaters help keep your tank clean by consuming algae and rotting matter.

5. Rasboras

  • Size: Up to 6 inches
  • Care level: Easy
  • Temperament: Peaceful
  • Water parameters: 72–81°F, 6.0-7.8 pH, 2-15 dGH
  • Tank space: 10 gallons

Here’s another excellent community fish. Rasboras have the perfect temperament and body size to be Corydoras’ tankmates. And you need only 10 gallons for one small shoal of fish.

If you’re looking to add some color to your aquarium, the humble Rasbora got you covered. This fish comes in orange, red, gold, silver, blue, green, and black.

6. Gold Barbs

  • Size: Up to 3 inches
  • Care level: Easy
  • Temperament: Peaceful
  • Water parameters: 64-75°F, 6.0-8.0 pH, 5-19 dGH
  • Tank space: 20 gallons

Gold Barbs have golden shimmery scales with irregular dark spots. They have a peaceful disposition and get along well with other friendly fish like Corydoras.

Despite its modest size, the Golden Barb can be quite space-demanding. You’ll need at least 20 gallons for a small group of 5-6 fish.

7. Rainbowfish

  • Size: 2.3-8.0 inches
  • Care level: Easy
  • Temperament: Peaceful
  • Water parameters: 74–80°F, 6.5–8.0 pH, 10–20 dGH
  • Tank space: 15-30 gallons (depending on the species)

There are over 50 known species of Rainbowfish, so there’s some variation in body size and space requirements. Most popular Rainbowfish are on the smaller side (4 inches and under) and require just 15 gallons.

Appearance varies depending on the species, but all Rainbowfish have the signature iridescent body with multiple hues.

8. White Cloud Mountain Minnows

  • Size: 1.5 inches
  • Care level: Easy
  • Temperament: Peaceful
  • Water parameters: 64-78°F, 6.5-7.5, 5-19 dGH
  • Tank space: 10 gallons

These Minnows have silver and green iridescent scales, pink and black horizontal stripes, and red snouts and fins. The White Cloud Mountain Minnow is the smallest fish on this list.

However, despite its tiny size, this species is known for its energetic and powerful swimming style. Minnows won’t have issues keeping up with the current in a Cory tank.

9. Silver Hatchetfish

  • Size: 1.5-2.0 inches
  • Care level: Difficult
  • Temperament: Peaceful
  • Water parameters: 74-83°F, 5.8-7.0 pH, 2-12 dGH
  • Tank space: 20 gallons

The Silver Hatchetfish gets its name from its unusual body shape. The laterally-flattened body makes this fish look like a hatchet from the side.

Despite its strange proportions, this fish is a rapid swimmer that loves a strong current.

However, this fish is a bit more difficult to keep. Hatchetfish have narrow water parameters and need a pH lower than most fish. It takes diligence to accommodate Hatchetfish with other species.

Conclusion

Unlike most other fish, Corydoras enjoy hanging out close to the filter, powerhead, or air stone. That’s because Corys like strong water currents.

Areas of the tank with the most water movement provide the perfect opportunities for Corys to play and stay active. If possible, bumping up the flow rate will benefit your catfish.

Of course, there can be too much of a good thing, so don’t overdo it. If your Corydoras have trouble resting, eating, or breathing at the surface, you must reduce the flow.

And remember— not all Corydoras like the same water flow. Many species love swimming against strong currents. Some find strong currents stressful and prefer gentler water movement.

avatar I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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