The butterfly standard was introduced in 2021, although the fish have been seen in the UK for the last twenty years, and longer in the Far East. The butterfly is similar to the fantail, with short, rounded fins, but the distinguishing characteristics are the globe eyes and the horizontal double tail, which is divided (unlike that of the tosakin, which is partially divided). The UK colour standard is for self-coloured metallic, variegated metallic or calico fish, as illustrated below.
Butterflies are called butterfly telescope goldfish or butterfly moors in the Far East. They are called butterfly goldfish in the USA.
The butterfly standard is as follows:
The fish should be bright and alert. The body should be short and rounded. The caudal fin should be well divided and shaped like open butterfly wings when viewed from above, and it should be at least 75% of the length of the body with the extremities being slightly scalloped in shape. The caudal rays should have the strength to support the tail spread with the lower lobes turning forwards towards the fish’s head.
The eyes should be large, prominent, with good development and well matched. Note: the eyes are large and spherical, set within raised sockets, as in the moor, and not the same as for the globe eye.
Metallic fish may be self-coloured (red, orange, yellow, blue, brown or black) or variegated (any combination of red, orange, yellow, blue, brown, black and white) in a pleasing pattern similar on each side. Quality fish will have high colour intensity and metallic shine extending into the fins.
Calico fish should have a blue background with patches of violet, red, orange, yellow, brown and white, spotted with black. Quality fish should have a high intensity of colour evenly distributed over the body, with colour, especially black, extending into the fins.
Ideal profiles are illustrated below:
A young, metallic yellow/silver-white butterfly. Shown at BAS 2001.
Chinese red-white metallic butterfly tails; the lower image shows the clear, horizontal lie of the tail when seen from the rear. (Hong Kong 2003).
Photo of the eyes of the butterfly, taken by Jackie Pedley, 2020-21.
© Bristol Aquarists' Society