I've only fished for catfish at Vasona Lake in Los Gatos. Here's what works for me. For tackle I use a light action spinning rod filled with 6-8 pound test. On the business end I have a small swivel (to prevent line twist) and a 1/0 octopus hook a few feet below it. Only if you need to cast very far will I add a egg sinker above the swivel. For bait I buy a whole mackerel at the nearest fish market. Fillet it the morning you fish and keep it on ice. Use a chunk of fillet about 1x2 inches. This will be heavy enough to cast with a spinning rod and 6 pound test with no weight. Throw it out into the middle of the lake (points are the hot spot for me), put it in a rod holder, leave the bait open, and wait. When a catfish takes it, they don't mess around. Set the hook immediately.
Bay Area Hotspots for Catfish: Vasona Lake, Coyote Lake, Uvas Reservoir, Campbell Perc Ponds, Arastradero Lake, Boranda Lake