The Android Market is riddled with below-average fish or koi pond live wallpapers.... Developers just haven't been able to release fish pond apps for Android that are as impressive as the ones on the iPhone/iPad. Well that all changes with the release of Koi Live Wallpaper from developer Kittehface. It has fluid water animations and looks great. Definitely my favorite fish/koi/aquarium themed live wallpaper. Anyway, the free version is pretty good, but doesn't allow you to customize settings (fish size/color/amount, rain drops, etc). You can pay 99 cents to unlock those.
Video Review ---
Market Link
If you know of any similar LWPs that are better, let me know because I haven't really found any that can compare. Kittehface always puts out quality LWPs too.