If you find it difficult to break free from the thrasher from the upgrade aquatic mod，the mod provided a method.

When you're bitten by thrasher,press "R" to cause 2 to 10 damage points to thrasher,at the same time, it will also receive a three second weakness effect.

This only works when you hold a weapon.An effective weapon can be a trident, sword, axe, and anything you set in config.