Barry wrote:

Hi, I saw a snake in the pond as I fed the fish!

I don't know what is was as it moved quick!

Will it do any harm?

Well, it's there for a reason - they can catch & eat fish, frogs & toads.
otoh, I've never lost anything important to them and I let them be. Of
course, it helps that I've never lived anywhere where I might come across
_poisonous_ snakes, or kept expensive fish. ymmv.
--
derek