Hanging shelves on a Cinderblock wall?

If your shelves are less than 8" wide, Tapcons (concrete screws) should be adequate, I would consider anchors if your shelves are 12" or wider, or, carry substantial weight. That being said, I have a shelf about 2' Square that holds a mini-fridge in my garage, and it holds just fine with Tapcons. However, I used shelf brackets that are substantial, at least 12" long and tall, and that makes a lot of difference, since most of the down-pressure is shearing force converted by the bracket, rather than pulling force.