This fish has an undivided double tail, with the tail splayed sideways and forwards. It was developed in Japan from the ryukin, and is uncommon outside Japan.

Tosakins were bred for viewing from above, and much of the effect of the spectacular tail is lost when viewed from the side. This is the only recognized goldfish variety with an undivided double tail: the two layers of the tail are split apart and grow separately from each other but are joined along the top edge (although, in that the tail is splayed sideways, it no longer appears to have a conventional top edge).