Why catfish react to the sound of the catfish clonk: Debunking myths and getting to the bottom of the truth

Greetings, fellow anglers! Today we're tackling one of the most fascinating topics when catching our whiskered predator: Why does the catfish rise to the sound of the catfish clonk? What does this "hydro-shock" really imitate?

Countless theories and myths circulate among catfish anglers about the Clonk fishing area. Some sound logical, others are simply bizarre. Before I share my opinion, which is based on years of experience and scientific research, let's look at the most popular "folk versions" and clarify why most of them don't stand up to critical scrutiny.

Myths you should no longer believe:

Theory No. 1: The catfish clonk imitates the croaking of a frog.

This is probably the most widespread misconception. First, let's be honest, the sound of a catfish clonk is fundamentally different from a frog's croak. Second, catfish can be attracted very effectively with a catfish clonk in waters where there are no frogs at all – for example, in large reservoirs or shipping canals. The main argument, however, lies in physics: A frog's croak is a sound that travels above the water (through the air). The sound of the catfish clonk, on the other hand, breaks the water column and travels directly to the bottom. While catfish do react to the splashing of frogs, the acoustics of the clonk's knocking are of a completely different nature.

Theory No. 2: The Clonk is the call of a female (mating call)

A very romantic, but unscientific version. To this day, there is no evidence that female catfish make sounds to attract mates. Catfish only spawn once a year at a specific water temperature (they aren't dolphins or humans, who spawn year-round). The catfish clonk, on the other hand, is known to work in both early spring and late autumn (I've personally used it to attract catfish in water as low as 5 degrees Celsius). Furthermore, both females and very small, immature juvenile catfish bite when struck with the clonk. It's unlikely that a mating call would attract them.

Theory No. 3: The sound resembles that of predatory asps.

It is said that the asp is the catfish's favorite food and that the catfish clonk imitates its surface thumps. However, I have personally caught dozens of catfish in waters where asp have never been found. The catfish is an intelligent fish and adapts to its food source, but attributing the reaction to the clonk to a "genetic memory" of asp is untenable. The catfish is not an alien, but a fish with highly developed sensory systems (barbels, sense of smell, lateral line organ).

Theory No. 4: The catfish lashes its tail to defend its territory.

People believe the catfish clonk sounds like a catfish's tail slapping on the water's surface. Yes, catfish do slap their tails (to mark territory or perhaps to get rid of parasites, similar to carp). But ask yourself: if a giant is announcing, "I'm the boss here!" in this way, why would other catfish (especially smaller ones) swim directly to the source of this threat? Furthermore, if it were just simple splashing, we could catch catfish by simply hitting the surface with a paddle. But we use a special tool.

So why does the catfish really rise? Let's get closer to the truth.

Having put the fairy tales aside, let's move on to the more realistic explanations.

Curiosity and food associations

The catfish reacts to vibrations – be it a crow that has fallen into the water, a duck landing, or a feeding predator. It has excellent hearing (incidentally, the warmer the water, the better the catfish hears). The sound of the catfish clonk is also very similar to the sound a catfish makes when feeding. Unlike the pike, the catfish doesn't seize its prey with its teeth – it opens its enormous mouth, creates a vacuum, and sucks in its prey with a characteristic, dull "pop" sound.

Everything seems to fit: The catfish hears a fellow catfish feeding and swims to the "buffet." But there's a "but": I've observed several times how a catfish rose to the sound of the clonk and followed the boat for over a kilometer! It swam behind, examined the bait, but didn't bite. If it had been hungry, it would have attacked. The catfish clonk can coax an absolutely passive, satiated fish up the slope in the midday summer heat. So it's about more than just food.

Irritation factor and hydrocephalus

The catfish has virtually no natural predators in the wild (above a certain size), so fear is foreign to it. It is incredibly curious. It is interested in the vibration of an anchor rope or the tapping against the hull. But the catfish clonk is more than just a tapping sound. Wade into the water up to your waist and give it a good, strong strike – you'll feel the hydrostatic shock in your legs. That's physical pressure. For a catfish lying quietly on the bottom, this is a massive stimulus. Imagine your neighbor starts hammering away at the wall with a jackhammer on a Sunday morning. At first, you tolerate it, then you get up to see what's going on. The catfish does the same thing. It rises up in aggression against the disturbance, sees a bunch of wriggling earthworms in front of it, and snaps reflexively.

Scientific fact: The communication of catfish!

And here we come to the most important point. In 2005, Dutch biologist and bioacoustics expert Herbert Tiepelt recorded strange underwater sounds during his research in the Netherlands. When these recordings, which were later included in international scientific databases, were played to an experienced catfish angler, he was shocked: The sounds were exactly like a catfish clonk!

They conducted an experiment: The angler tapped on the water with Clonk, and the scientist lowered a hydrophone into the water. And guess what? The catfish responded to the sound of the catfish clonk with similar acoustic signals! The researchers concluded that catfish actively communicate with each other by abruptly contracting special drumming muscles that act on the swim bladder.

What they are "talking" about remains a mystery to science. But today, most biologists tend to theorize that the catfish clonk imitates precisely this language of catfish. This discovery confirms that the catfish is a much more "social" fish than previously thought. Its reaction can therefore be triggered by hunger, territorial instinct, or pure curiosity.

That explains everything: why different tones are needed, why some taps attract and others repel (you wouldn't shout at someone if you wanted to have a calm conversation). Essentially, by tapping, we enter into a dialogue with the fish.

Conclusion

Friends, we could come up with many theories. Communication, attraction, curiosity – most likely, the catfish clonk is a combination of all these factors. But remember the most important thing: theory remains theory, and the fish is caught by the one on the water. Grab your clonks, experiment with the frequency and power of your strikes, and go find your fish!

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Vitali Dalke