2 button cell batteries must be inserted into the bottom of the fish. For this, the Phillips Screw is gently turned until the cap rises. When not screw it tighten. Best of hand. Fish move the tail to the button cells after about 2 hours are empty. In Fuktion remind them of live fish, because they submerge and swim along the bottom. The movement sometimes sets out for a short time and they come to the surface and then dive again.
