Is there a "clean" lubricant that can be used on tools for use in water?

I just bought a tree pruner intending to use it to trim water lily stems in my backyard pond, which has lots of plants and fish in it. As soon as I put it in the water, i noticed a sheen of lubricant oil on the water, and I'm concerned it's polluting my pond with nasty chemicals that may damage the water quality and harm my plants and fish. I'm thinking of stripping off the current lubricant with solvent and replacing it with something I can feel more confident about (and obviously it would need to be water-resistant too), but what might that be? Any suggestions?