Electrophysiological studies of spontaneous retinal degeneration in celestial goldfish (chotengan)

Spontaneous retinal degeneration of Celestial goldfish was studied histologically and electrophysiologically. Retinal degeneration was divided into three stages. Until the age of 75 days (Stage 0) the retina showed normal histological development and the electroretinograms (ERGs) exhibited dominant b-waves similar to those of adult common goldfish. By the age of 105 days (Stage 1), when the eyeballs began to protrude laterally, histological changes were first observed in the retinal pigment epithelium and photoreceptor layer. The b-wave amplitude decreased to 52% of that of Stage 0 with a prolongation of the peak latency. By the age of 135 days (Stage 2), when eyeballs protruded further anterodorsally, the retinal degeneration extended to the entire retinal layers and no b-waves were detected. The deterioration of the b-wave amplitude was closely correlated to the histological findings of retinal degeneration. The Celestial goldfish is considered to be a new model of hereditary retinal degeneration.