The bottom bag A Fuji-type lead chain cast net is a fishing gear used to cast or throw into the water for fishing. This net usually has a lead chain around its perimeter to help it sink to the bottom quickly. The “bottom bag” design allows the net to capture fish efficiently, making it a popular choice among anglers, especially when targeting fish near the waterbed. Fuji-style cast nets with lead chains are known for their effectiveness in catching fish in a variety of aquatic environments.