Here's a quick video of a biotope loosely based around a Costa Rica River system.
[video=youtube;h2GySuJ8yJM]http://www.youtube.com/watch?v=h2GySuJ8yJM[/video]
[video=youtube;h2GySuJ8yJM]http://www.youtube.com/watch?v=h2GySuJ8yJM[/video]