Just thinking outloud. Looking at the picture, the pond is probably old and well shaded as you said. Since it hasn't developed vegetation by now on it's own I would personally try some aggressive evasive plants. Maybe thin the trees to get some sunlight. Life starts with plants, for eating, oxygen, bugs and structure, etc.

With all of the predators you have it looks like the fish will eat each other up and all will starve that are left. I'm certainly no expert so there's better advise on pond boss.

Last edited by John Monroe; 05/13/15 05:10 AM.