I'll build guards around any trees I plant, but will likely not put much else out there.
As far as cover for the fish, I've already been working on that. I have done enough research to know that it's NOT absolutely necessary to have anything for cover. You just accept the fact that fish will be fish and eat each other, lol. Some predation is necessary so the fish don't overpopulate which would stunt their growth.
However, I like the idea of a more "natural" environment for them so I added several objects that can be used for cover. I had a terra cotta "fish" fire pit that DH bought for me years ago. Similar to this:
At some point in time, it had its tail broken off. We still used it, but it was definitely compromised, lol. That tailless fish now resides at the bottom of the pond. Also, a large, broken terra cotta planter was added. Some sections of pine logs that I had been soaking for weeks so they would sink were placed in three different locations before the big rain. I'll be watching for discarded trees after Christmas as they are widely accepted as great habitat for smaller fish.
IF I ever get bamboo I'd definitely stick with the clumping types and not the running type. I had a former co-worker who bought a house with a bamboo border along her back fence. Her husband would simply mow around it, and it kept the runners in check. He was very diligent about it!
We've got some sunshine today, yay! It was 47 when I got up and headed for a high near 70. Should be a great day to be outside - with mud boots of course!