I believe I do have a timeline of events that you might find revelatory.
His daughter, Toby is hostile to the idea of fishing and confronts him as he arrives in. Russ explains that he doesn’t actually use a hook, so all he is really doing is “fish feeding”.
After Toby leaves, Russ and Alex talk more about Russ’ pretend fishing. Apparently, Cliff doesn’t know that Russ deliberately doesn’t catch fish. He just thinks that Russ is bad at fishing, which he enjoys teasing him about.