I have a duck pond with mandarin ducks, canada geese, mallards, mute swans, indian runner ducks, mallards, white farm ducks, greylag geese, white farm geese, herons, coot, moorhen and water rail. What is the diets of these birds?

You have all those bird species?!

The ducks, geese, and swans mostly eat aquatic vegetation and some land vegetation. They sell waterfowl feed which is mostly grains to feed them. On occasion, they may take small fish, aquatic invertebrates, etc.

Herons eat fish, snails, tadpoles, and frogs.

Coots are omnivores, eating both plants and small animals (fish, tadpoles, insects).

Rail mostly eat aquatic animals like those previously mentioned.

Moorhen are omnivores, eating plants, grass, insects, snails, worms, etc.

I have added lots of minnows for the heron and I am feeding the birds grain. The heron enjoys grain too.

How do you keep all those birds around? Are their wings all clipped? Is it all fenced? How big is the pond? Did you buy all those birds or did some just show up? I don't think you can buy herons and rail legally? The others I've seen for sale although not sure about coots and moorhen. Just curious!

The rail, coot, moorhen and herons are natural. They flew from the park pond.