I have a few extra fish tanks that I am not using anymore. They were used for fishes. I have a 10 gallon with the background still on it and I also have a 20 gallon BOW tank with the background still attached to it as well. I have one regular 20 gallon and a 55 gallon fish tank as well. All in good condition. All used recently except for the 55 gallon, but the last time it was used it held water fine as well.