put a half a cup or so of tank water in cup, add cube and let thaw out. once thawed drain off juice and keep solids, add more tank water to cup, add couple drops of selcon, or other , and let soak for 10 minutes, add to tank. many ways to do it you will have to experiment. basically never add frozen cubes directly to the tank, drain off juices and only feed solids. the selcon is to boost or fortify the natural food. no really required but recommended.