Protogynous Sex Reversal in the Fish Anthias squamipinnis (Teleostei, Anthiidae) regulated by the Presence or Absence of a Male Fish

Abstract

PROTOGYNOUS or protandrous hermaphroditism among teleost fishes has often been described¹. Although found in various families, the phenomenon is especially common among Serranidae and closely related groups. It was briefly mentioned for the Mediterranean Anthias anthias^2,3. While working on the ecology and reproductive behaviour of the Red Sea fish Anthias squamipinnis, D. Popper and I (unpublished results) found protogynous hermaphroditism and intersexuality in this species which was confirmed by N. Gunderman and me (unpublished results) when we observed changes in the gonads⁴. To establish whether environmental factors regulate this sex reversal, or if it is a continuous and non-predictable process, I carried out a series of experiments with Anthias performed in captivity during 1968 and 1969. When ten to twenty females and one or two males were kept together for several months there was no change in morphology or behaviour to indicate sex change, although cut sections of these fishes revealed advanced degeneration of the ovaries.