Are stonefish eatable

No... a stonefish is venomous, not poisonous. Poisonous states the the poison is always active. Like a poison dart frog, the poison is always on the outside of its body. But venomous is when it has to be outputted somehow. Like on a stonefish, you have to step on the spine for the venom to come out, otherwise, if you touch it, nothing will happen.