Ya know, plastic mesh is available from 3/16" openings all the way up to about 2" openings. That's what the fish cages are made of. No metal to rust, no zinc to bother the fish, no rough wire to damage the fish in the cages. It's available in rolls that are 4' wide.........
And if you bought a small roll of it use on your spillway guard, I bet you could find other uses for the rest of the roll around your pond!