Leeches

Pond questions - leeches

I'm planning to do a bit of pond cleaning one of these days. I'm not looking forward to it though due to me finding a large number of leaches below one of several rocks in my pond. They're quite small, about 1 cm in length, probably because there isn't much in the pond to suck blood out of. I've got about 20 goldfish in the pond and I've never seen one of them with a leach attached to it.

Is it normal to have leaches in ponds?
Where did they come from?
Is it safe to get in the water without getting some horrible disease from them?
Will the leaches latch onto the goldfish, or will my fish eat the
leeches? (probably both)

Answer:
Leeches or blood worms are harmless and quite normal in ponds, although we don't like them. They can help your pond by eating some of the organic matter trapped in your filter. They will be eaten readily by the fish and are carried in, as eggs, in bird poop. Birds are the carrier host. The type primarily found in our ponds are not the swimming type, so the fish are safe for the most part and they will usually be found in filter matting where the fish can't get them.