This talk will give you an overview of the use of Optical Tweezers in biology, and more specifically in zebrafish and its vestibular system. Otoliths, or ear-stones, play an important role in zebrafish for hearing, its sense of balance and acceleration. Many studies have been conducted to understand its structure, function but also development conditions. However the encoding in the brain as a movement sensor remains unknown. Here we developed a non-invasive optical method capable of manipulating one or two otoliths simultaneously in different directions to simulate movement or acceleration and sound. Our system uses optical traps created with an infra-red laser at different positions on the otoliths creating forces in chosen directions. I will also present our latest result on brain imaging in response to artificial acceleration and sound.