Abstract: The invention relates to a method for processing fish of the Trachurus species and an apparatus for performing the method.In order to obtain top quality products of this fish type and which a high yield, there is provided a tool for removing the bony structure at the end of the abdominal cavity which is prejudicial to precise processing. The tool comprises two circular knives acting as abdomen openers and in whose gap where is arranged a guide member with a sharp leading edge and covering the upper rear area of the cutting edges, which guide member removes the fin ray support (pterygophore) of the anal fin overlappingly connected to the first belly spoke (haemapophyses of the eleventh vertebra) together with the anal fin and the abdomen edge, so that no bearing or rearing up of the tail area impeding the separation of the lateral keeled scales, in particular, occurs.