Ranchu tail. The caudal peduncle itself should be broad and neither lengthy or too short (a properly formed caudal peduncle avoids swimming motion impairments to this type of goldfish). The ranchu's tail meets the caudal peduncle at a forty-five degree angle, giving the fish a unique swimming motion. Furthermore, the tail lobes are rounded, and all other finnage are paired. The most prominent feature of the ranchu is its head. There must be sufficient space between the eyes, and also from the eyes to the front of the head. The gill cover should figuratively extend quite far towards the tail. The
Operculum (brain) Operculum (brain) In human brain anatomy, an operculum (Latin, meaning "little lid") (pl. opercula), may refer to the frontal, temporal, or parietal operculum, which together cover the insula as the opercula of insula. It can also refer to the occipital operculum, part of the occipital lobe. The insular lobe is a portion of the cerebral cortex that has invaginated to lie deep within the lateral sulcus. It sits like an island (the meaning of "insular") almost surrounded by the groove of the circular sulcus and covered over and obscured by the insular opercula. A part of the parietal lobe, the