During peak summer heat, where do Wels catfish generally seek thermal refuge during daylight hours?

Below the sharp thermocline in cool, oxygenated depths

Wels catfish are described as warm-water fish that require thermal stability, especially during the heat of summer. When surface waters warm considerably, they retreat to the deepest parts of the water body to regulate their temperature. For anglers utilizing modern sonar, identifying the thermocline—the boundary layer between warm surface water and cold deep water—is a key indicator, as the catfish typically position themselves just beneath this line, utilizing the cooler, oxygenated depths near the bottom for resting.