Pearlscale

this pearlscale has no head headgrowth

The pearlscale or chinshurin in Japanese, is a spherical-bodied fancy goldfish with finnage similar to the fantail.[1][2]

Description
The characteristic feature of the pearlscale is its thick, domed scales with pearl-like appearance.[1][3] Its body is round and similar to a golf ball. The finnage may be long or short. Pearlscales can reach up to 8 inches long and grow up as large as oranges.[3] However, pearlscale fancy goldfish are prone to swimbladder disorders which affect the ability to maintain normal position in the water. This is attributed to the selective breeding process of fancy goldfish to achieve particular body forms, such as that of the pearlscale's. Selective breeding gradually resulted to the alteration of the appearance of the swimbladder.[1]

Coloration
Pearlscales come in every color variety.[3]

Variants
Pearlscales are found without headgrowth, with Oranda-like headgrowth or with two large bubble domes. The bubble-domed Pearlscales are known as High-head pearlscale or Hama nishiki.[3]

Special temperature requirements
Pearlscales are very sensitive to cold water and should not be exposed to temperature readings below 55°F (13°C).[1]

http://en.wikipedia.org/wiki/Pearlscale