Howard, They are frog tadpoles, possibly leopard frog as Bob says or if you have bullfrogs in your area they they could be bullfrog tadpoles since the body apprears about the size of a penny. Regardless of which species they will cause very little problems in the pond. Fish do eat them but not readily unless other food items are in short supply. They tend to have an off flavor but not to the point that no fish will eat them. Once you put bass in the pond you will see a lot fewer tadpoles. Frog & toad tadpoles have long coiled intestines, are herbivours, and consume a lot of attached and filamentous algae algae.
