In Aquaria, players take on the role of enthusiastic members of an aquarium club, each determined to create the club's most beautiful aquarium! Each player maintains their own aquarium, home to a variety of fish and aquatic plants.

During the game, players buy new fish, feed their animals, and keep their aquarium in perfect condition. They also demonstrate their progress as an aquarist by completing steps on the encyclopedia paths—which represent milestones of knowledge and expertise.

Whoever has collected the most points at the end of the game wins the title of best aquarist!