What describes the diet flexibility of the Wels Catfish as an apex predator?

It consumes fish, mollusks, crustaceans, insects, and amphibians

One of the cornerstone elements enabling the Wels Catfish to maintain its status as a generalist apex predator across numerous European systems is its incredibly broad diet. This flexibility means it is not dependent on any single food source for survival or persistence across changing ecological conditions. The range of items consumed is extensive, explicitly including fish, mollusks, crustaceans, insects, and amphibians. Furthermore, large individuals are known to supplement this aquatic diet with terrestrial items such as small mammals or birds that venture near the water's edge. This opportunistic feeding habit contributes significantly to its success both in its native waters and when introduced to new environments.