Ally, now that you mention it, that's a part of my plan. Last summer, my filter and pond clarifier wasn't cutting it, and now that the pond has made it through the winter I am totally overhauling the system. That includes a nice, big UV filter which I recently purchased, so that should definitely help.
All that I have to do is dig, do some stone and pond liner buying, get the filter and pumps up and running, and perhaps restock the pond once all systems are go.
As for what is in there now... a nice infestation of Gambusia
, as mentioned, and Japanese Black Trapdoor snails (love those guys - I need to get some pictures for you) and various pond snails.
In the past (and at separate times), I have had red eared sliders, koi, comet goldfish, rosy red minnows, bullfrog tadpoles, ryukin and fantail goldfish (which aren't good pond occupants, really), and some others which escape me.
Concerning the pond itself, this is really just a small project I decided to dive into (
) a while back. I've always been a sucker for ponds and it creates some nice scenery in my bird feeding spot where I do all of my song bird watching. I can dig a little into the ground to make it deeper (which I have done) but my yard is really not suited for a completely ground-level pond, which is why I decided to experiment with this small above ground brick pond (don't want dogs splashing through it, after all). Now that I have been fairly successful, I am hoping to expand quite a bit, maybe even completely remodeling. We'll see, but at least I have some new equipment to help out.
Thanks again for all of the comments