You can unlock the mermaid by having four corals. According to the game guide for inquiring about the Fat Goose Gym, mermaids need to have four-level corals first, and the function of mermaids is to detonate the drift bottle props according to the piano given by the players. Fat Goose Gym is a leisure and educational mobile game, which was released on September, 2020 1. Players will play the role of the manager of the gym, get materials through synthetic games, unlock new areas of the gym, new decorations and new fat geese. All gym decorations can be DIY in appearance and orientation, creating an exclusive gym to attract all kinds of cute fat geese to come to fitness.