My new 0.4A pond has about a grand total of 6" water in it right now, with a full pool max depth of 12' and an average depth of probably 7'. I clearly have a ways to go for it to fill, and am taking this opportunity to add structure before planned initial fish stocking next spring.

I've added some natural fall-downs and some man-made structure with natural logs, and am planning to add pallets. Along half of my eastern bank adjacent to a dock I have a pea gravel beach, which will help for launching kayaks and provide some habitat for BG spawning.

I don't desire to have riprap all around my pond, or even along a majority of my eastern bank (winds are prevailing from SW, but wind action on pond will be limited by trees), but I do see great benefit in having at least some rock piles.

It will cost me about $350 to have a triaxle of riprap delivered.

As an easier to source and move option, would using cinderblocks (since I have to buy some to weigh down my other structure anyway) and making irregular pyramids with them provide a similar structure benefit to rock piles?

It's my bet that cinder blocks (the kind with the big holes through them) would be an excellent choice, even superior to rocks. They maximize surface area for small biological growth and maximize cavities for the fish to hang out in.

There might be some pH concerns to consider depending on the water chemistry, but that would also be the case with natural rock depending on the kind. Minimal concern I would think, but worth researching.

Natural rock would be better for crawdads, however...imo.

I have to say...it depends, regarding the cinder blocks to some degree. If you want recruitment of your stocked fish, the added hidey holes will be good.

Cinder block piles are fantastic fish magnets. You don't want to put them where someone might accidentally run into them while swimming. Big ouchies.

Rip-rapped banks are also fantastic fish magnets.

Maybe think about doing some 3'-4' high cinder block piles in 6'-8' deep water, and a few rip-rap piles along the bank.

You'll want a loader machine to place the rip-rap. Cinder blocks you can just drive in with the truck and toss em off the back. It will be a lot easier to get it done before the pond fills.

I have found if you approach a brick/block supplier they typically have odd lots, overruns, returns, etc sitting in some back corner. If you pay for delivery, they will sell at no or low cost. It costs them more to dispose of them than to give them away. You might not get all the same block but what difference does it make after their underwater.

Yes the cinder blocks work well and it is best to do before the pond fills so you can arrange them in piles. If you have acidic soils the calcium in them should be beneficial.

I built a fish crib out of 5 pallets by tying the pallets together and then tossed in a dozen or more blocks into this open toped box. I then added a cedar tree to the outside of this fish crib. I did this in about 8 of water after the pond was full. I would have been easier if I had done it before the pond took on water. But is was not all that hard to do at full pool by adding the box and blocks onto my floating pier and then moved the pier with a trolling motor out into the area where I wanted the structure. it has made a nice fish attractor and I have caught a few fish off it. Floating piers have their benefits.