I have a ton (not literally) of cinder blocks laying around after construction of a new garage. Would it be beneficial at all to create a small 'rock pile' with these in 2-3 or 6 feet of water? I'd like to keep them within 15ft or so of the shore in between two docks (where no boats really go - minimize the change of someone knocking a prop) or out in about 6 feet between the docks, again so no one hits them.

Would this be of any benefit to any species of fish?