You haven't said just how small the pond is, but you will need an oxygenating plant or two in there - common fish weed sold in pet shops for use in fish tanks will do, usually sold in a clump with a lead weight at the bottom to hold it down. It grows under and in the water, and the base, complete with lead weight, should be pushed into an aquatic pot full of aquatic compost with gravel on top, then placed at the bottom of the water in the pond.
It is best to have some kind of pump though, which keeps the water moving and aerates at the same time.

if your not having fish you dont need a pump . lifewill find your pond thow as bamboo sais youl need a few plants to stop it going bad . as for frogs you need to actualy get the frogs spawn or at best tadpoles as adults have a homing instinct and youl find they will all try and get back to wear you caught them . tadpoles are about quit early so you mite find some now if your lucky .

I built my pond 14 years ago and the frogs and Newts just arrived with no help from me, the fish will be 14 and 12 years old this year and I have never had a pump. I do have oxygenating plants and each spring and Autumn I put 2 Barley straw bags, I never add chemicals or tap water this work for me in keeping it clear and healthy.

im not saying frogs wont sometimes find and use your pond . i remember thinking as a child that i wanted frogs/toads etc . went to a local pond caught a load of adults about a couple of miles away and put them in . next morning to my horror found all the amphibians gone over night . when i restepped my walk mainly to stock up on some more i found out what theyed done . all tried to cross roads to get back and lots of them squashed .ponds with plants in have been about without pumps id imaGINE FOR MILLIONS OF YEARS AS HAVE FROGS ETC . ITS JUST IF THE POND IS VERY SMALL the fish mite not make it which bamboo did mention .