Plastic garbage bag ribbon habitats will work for a short while. Once algae starts attaching to it and the layer builds up any sort of thichness the strips/ribbons will sink and no longer stand up. Typically one will usually place these bag habitas in shallower water where light penetrates and stimulates algae growth. Be aware the ribbons will not rot but they may not stand up for very long. Been there done that.
Another thing that is a similar sort of fish habitat is the plastic banding that is now used in many pallet or box binding applications. Cut the banding in lengths and weight them to the bottom using one of many different methods. Banding is more durable and will float quite a bit longer with algae build up than the plastic bag ribbons.
