Double fish

I was fishing this morning with a couple friends just off Mayne island, when I caught a small fish. While reeling it, it felt like I hit a snag. It wasn't fighting, it was just really heavy, so I thought maybe I picked up some seaweed or something; at least, until it reached the surface:

A bigger fish ate the smaller fish I caught, while I was reeling it in! Double fish, all the way! What does it mean?