Sorry I didn't respond sooner. I found out that it's called Utility Fabric - Black Laminated Burlap. The only drawback is that the goldfish poopy is not able to get out and into the pond pump. I would love to find the same material but with 1/4 inch openings.I'm not picturing this fabric. Could you find a picture on the internet and post it for me?
http://www.onlinefabricstore.net/images/products/BURBLA_1.jpg