Can spiders really catch fish

Yes.

There is a genus of Australian Spiders known as Fishing spiders (Dolomedes instabilis), of the family Pisauridaewhich, as their name suggest, catch fish, as well as tadpoles and frogs. These spiders have long, strong legs, and tend to rest by the edge of still ponds, with their legs touching the surface of the water. This suggests that these spiders can detect prey by touching the surface of the water: as prey approaches, the spiders will skim the surface of the water to catch creatures such as insects, small fish and tadpoles, and sometimes even submerge to catch them. They also lightly touch the water surface with their legs to lure fish closer.