The Froak is a puffer fish-like monster that will fly towards link slowly with its spikes outstretched that will do a small amount of damage on contact.
The Froak is a danger up-close as when it is destroyed it will explode like a Bomb Flower. Froak's will only protrude it's spikes if Link is too close to it and while its spikes are out you cannot kill it by hitting it but, only kill it by knocking it into a wall. Froak's have two weaknesses: one is to knock it into a solid object like a wall with ether the Gust Bellows or most other impact items (not including the Whip). The other is hitting it with an impact item before it's spikes are out from a distance.
Froak's can be used like Bomb Flowers to blow up walls and deal damage to other enemies if close enough. Froak's can also be found underwater and be tackled while their spikes are out with the Water Dragon's Scale to knock them into something, since you cannot use any weapons underwater.