These nutritious blocks are suitable for any freshwater aquarium and are designed to slowly dissolve and release food particles over the course of a long weekend to provide fish with a constant supply of their diet while you're away. Simply drop into your tank and allow to dissolve. Recommended for pet owners when away from home for the weekend. Shell-shaped blocks slowly release contained food through outer shell. 2 blocks can feed up to 10 goldish or 20 tropical fish for 4 days. Helps to contribute essential nutrients and minerals to maintain great everyday physical health and wellbeing. Suitable for tropical fish and goldfish. Suitable for freshwater aquariums. 20g. Vitapet products are distributed by Masterpet, a company with over 50 years of experience. Created on the belief that life is just better with a pet, they strive to develop specific products for the specific needs of pet owners. Their products are always known for their quality and reliability.