It is well known that the differences in the spawning behaviour of teleosts
can to a certain extent be illustrated on the basis of the condition revealed
by • the unspawned eggs in the ovary (Heidrich, 1925; Clark, 1925, 1934;
Hickling and Rutenberg, 1936). Many studies on the ova diameter frequencies
have been undertaken during recent years and in almost all cases
it has been accepted that species which have all the ovarian eggs of similar
size spawn them together whereas those which have a wide range in oocyte
sizes may have several groups of eggs matured and shed periodically during
the breeding seaso