Hmm... I built a pond last summer as a pandemic project, and just got koi in it a couple months ago. I haven't really thought seriously about aquaponics, but I seem to have most of what I would need right there already if I wanted to start growing something. (Maybe lettuce?)

Right now, the pond has a lot of regular pond plants, including azolla (aka mosquito fern or fairy moss) which about every week or two I cull about a bucket's worth and feed to the roommates's chickens so it doesn't take over the whole surface.