A protective device for animal breeding, such as the breeding of fish, mussels or molluscs, comprises at least an inner cage (15) that can be positioned in a body of water (11) and which is formed from a net (16). This cage (15) is dimensioned here with a mesh width (16’) such that the animals to be bred are retained within said net. It is preferably totally surrounded by at least one outer cage (20) spaced apart from the latter and which is produced from a net (21) made of thin wires (22) and/or strands. The mesh width (26’) of the outer cage (20) is greater than that of the inner cage (15), and it is thus guaranteed that predators can not damage the net (16) of the inner cage from the outside.
