That's a very pretty pond you have!
I have really enjoyed working with my freshwater shrimp over the last few years. I have recently been keeping some in an invertebrate only aquarium with scuds. I am amazed at just how smart they are! They see me come in the room and come up to the surface, flip upside down and begin swimming in circles waiting to be fed flakes.
Try to find out what species of shrimp they are... That would be a big help in determining if they would be suitable for your pond.
