Wow, great looking pond! Is that sand all over the bottom or clay? Hard to tell.
If you have boulders available, I would order a variety of sizes and a few loads. As mentioned, limestone would be beneficial. Then rent/hire a skid-steer to place them around the pond basin making huts, cavities, and caves (aka Love shacks). They should become excellent places to dangle a hook.
I didn't have the ability to move stones larger than 2' without a skid-steer, but of the "love shacks" I made, the fish are always around them or in them. I built one that had about a 5cu ft interior with my son that wound-up being about 12' under. I snorkel down to it and find perch in there all the time staring back at me. They love it! The FHM on the other hand used to think it was theirs, not the best home for them any more.
That is clay. We have about 3-5' of sand on top and then clay down to at least 23'. I know rocks will be my best bet but the expense of them may be an issue! It is a long way for shipment and the cost of delivery is what will get us. I've got plenty of tires and pallets so that may have to suffice.
What about cedar posts tied together in a teepee like setup? Would that work? Have access to unlimited cedar here in the hill country of Texas.
