• Aquarium keeping is a popular hobby in the Western world. • Aquarium keepers have a moral duty to keep their tanks clean and their occupants happy. • Eco-friendly solutions can be applied to aquarium maintenance, such as using eco-friendly filters, introducing algae-eating animals, and switching to a self-sustaining aquaponic system. • Applying eco-friendly principles is important for preserving the environment that supplies aquariums with flora and fauna.