Hmm sounds more expensive, but I've not checked into what the rocks will cost.
Might be different for your area, but the use of suitably sized rocks (collected, loaded, transported, deposited and properly positioned) would cost a bundle down here. Bagged concrete is readily available in palletized quantities, and is
relatively easy to haul, unload and place along the exposed shoreline.
Is that sand based concrete or gravel like a sackcreat? Would lime leaching from the concrete hurt the fish?
Not sure John, but I'd guess a sand-mix concrete. Also not sure about the type of lime used in concrete (is it hydrated lime?), but I certainly don't think any potential leachate would affect resident fish. Ag lime is commonly used in many areas to increase pond-water alkalinity.
