The releasing fishing spear is a tool for fishing from the inside diameter of fish. It is mainly used for fishing drill pipe, tubing, casing and so on. According to the specific situation, it can cooperate with internal cutter, jar and other tools. If the fishing operation fails, the spear can be easily released from the fish. The releasing fishing spear consists of mandrel, grapple, release ring and nut. Each specification of fishing spear is equipped with different sizes of grapple for fishing operation. PetroZHR circulating and releasing overshots are designed for efficient downhole fishing with the ability to circulate fluid while engaged with the fish, and to release quickly if the fishing operation needs to be abandoned.