It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import.
import crafttweaker.entity.IEntityFishHook;

IEntityFishHook extends IEntity. That means all functions available to IEntities also are available to IEntityFishHook.

ZenGetter	GetterMethod	返回值类型
ZenGetter caughtEntity	GetterMethod caughtEntity()	返回值类型 IEntity
ZenGetter angler	GetterMethod getAngler()	返回值类型 IPlayer

SetterName	SetterMethod	参数类型
SetterName lureSpeed	SetterMethod setLureSpeed(lureSpeed)	参数类型 int
SetterName luck	SetterMethod setLuck(luck)	参数类型 int