Feeding Behavior of Catfish: New Scientific Findings

Science meets Angling Practice: The Feeding Behavior of Catfish in European Waters

The European Wels Catfish (Silurus glanis) is not only the undisputed giant of our freshwaters but also an extreme chameleon when it comes to its diet.

While the current study by Yazici et al. (2025) from the Anatolian Sıddıklı Dam reveals exciting basic principles of its behavior, a look at other European research findings shows how radically this fish adapts to a wide variety of habitats.

The results highlight the catfish's "trophic plasticity" – its remarkable ability to flexibly adapt its diet to the available food supply, the season, and its own body size.

To understand – and ultimately catch – catfish, one must learn to "read" the respective body of water. Here is the current state of scientific knowledge on what truly is on the catfish's menu.

Ontogenetic Change: From Worm to Large Fish

The investigations from the Anatolian Sıddıklı Dam provide a perfect blueprint for the age-related dietary shift (the so-called ontogenetic change) of the catfish. Stomach analyses of 200 animals showed a clear pattern that is consistently confirmed in other European waters:

Young fish feed almost exclusively on bottom-dwelling invertebrates, crayfish (often over 50% of their diet), and insect larvae.

Medium-sized catfish primarily hunt smaller schooling fish.

Large specimens avoid the energy expenditure for small prey. In the studied reservoir, their main diet consisted of almost 80% large tench (Tinca tinca).

Furthermore, the study proved that catfish had by far the highest stomach fullness levels in winter – clear evidence that catfish are not purely "summer feeders" and that fishing in deep pools can definitely be worthwhile even in the cold season.

My note: However, it must be strictly noted that this study was conducted in the warmer regions of Turkey. It is possible that the milder temperatures there lead to catfish being more active in winter. But even there, the metabolism of catfish drops drastically in colder water in winter. In practice, this means that a catfish can take up to two weeks to fully digest its stomach contents. This very slowed digestive process is a very realistic explanation for the full stomachs in the winter months.

Extreme Adaptation: Pigeon Hunting and Deep-Sea Dives

Studies from other parts of Europe prove in sometimes spectacular ways that catfish are opportunistic predators. They don't just eat what's available in abundance but develop highly specialized hunting techniques for the most profitable prey.

The Pigeon Hunters of the Tarn: A world-renowned study from the Tarn River in Southern France documented how catfish completely adapted their behavior to hunt pigeons bathing on the shallow banks. The fish shot out of the water and intentionally beached themselves for a few seconds on the gravel to snatch the birds – a behavior that biologists had previously known almost exclusively from orcas.

Hunters of the Deep: A study on Lake Maggiore in Italy showed that catfish by no means only hunt in shallow or mid-water. Researchers proved that the catfish there dived to depths of over 60 meters to attack deep-dwelling prey fish.

Flowing Water vs. Still Water: The Menu Changes

A catfish in a river branch hunts completely differently than a conspecific in still water. This is illustrated by studies from large rivers such as the Ebro (Spain) or the Tagus (Portugal).

The "Interceptor" in the River: In flowing waters, catfish often position themselves strategically at current edges or weirs to intercept migrating fish species. While sedentary tench were the main prey in the Anatolian reservoir, catfish in large, permeable rivers (such as the Rhine) often specifically fill their stomachs with ascending eels, barbel, or shad.

The Invasion Effect: Studies show that catfish grow extremely quickly in waters they newly invade. They prey on completely unsuspecting prey – such as native waterfowl or large whitefish that have not developed a natural flight instinct against this huge predator over the course of evolution. As soon as this easy prey adapts to the new danger from the large predator, the catfish flexibly switch to crayfish or other prey animals.

Master of the Night

A behavioral study by the French research institute INRA investigated the day-night rhythm of these animals. It scientifically proved that catfish (especially when acting as solitary hunters) are strictly nocturnal predators.
My note: A known exception here is, of course, very murky water, which lets little light through anyway.
They do not rely on their eyes for hunting but on their highly sensitive sense of smell, their lateral line organ, and their long barbels. Through special electroreceptors, they can accurately perceive the fine muscle twitches of prey fish in complete darkness or in extremely turbid floodwaters. Interestingly, the study also showed that when catfish are in larger groups, this rhythm can break, and they may also hunt in broad daylight.

My note: From my own experience as an angler, however, I can add that I have often experienced moments when catfish were significantly more active during the day, even in relatively clear water, than at night. Science provides us with good guidelines, but there are no absolute rules on the water.

Conclusion for Angling Practice

What do we learn from this concentrated science? There is no one catfish bait and no one tactic.

1. Observe the ecosystem: Are there huge bream populations in the water? Then a large, solid bait is the first choice. Are there many waterfowl or rats feeding on the bank? Then noisy surface baits can provoke brutal bites in the shallow water zone.

2. Location dictates the method: In reservoirs (as in the Anatolian study), it is worth searching deep edges and open water zones (pelagic). In rivers, the fish are often where the current drives food directly to their mouths.

3. Be as flexible as the fish: If the classic baitfish is scorned one day, remember the catfish's gigantic spectrum. A thick bunch of earthworms, squid (calamari), or even large fishmeal pellets can often turn the tide, as they imitate invertebrate food or easy protein sources deeply ingrained in the catfish's hunting instinct.

Every body of water has its own laws. The catfish has perfectly adapted to them over the course of evolution – as anglers, we must do exactly the same.

Good luck on the water!
Vitali Dalke