How dare you belittle the power of toothpaste.
Original Colgate will repair a pretty good sized scratch on a cd. The tank is probably acrylic so a razorblaze will only make it worse and the plastic was eaten away by hard water. If toothpaste doesnt work then your stuck with it, View the fish from the other side. Toothpaste fills and replicates enamal on a tooth, it works great for scratchs, no lie. Its not crazy like oxy-clean, because that stuff would probably make that tank a toxic wasteland.
