Abstract: The apparatus disclosed relates to the fishing industry and incorporates a means of aligning the fish and a pair of circular knives mounted in hubs on a shaft with provision for their displacement along said shaft. According to the invention, the possibility for the knives to displace along the shaft is realized through the intermediary of a resilient member movably linked-up with the shaft and the hubs as well as through screwed joints of opposite directions provided between the shaft and the hubs of the knives. The recourse to the apparatus disclosed assures good economy of the process of severing the fillets from the backbone and fins of the fish under the conditions of mass production.