The advance of fish cytogenetic research was greatly enhanced by technical innovations in the preparation of metaphase chromosomes. The small size of fish chromosomes and their high number compared to mammalian chromosomes, and the then current squash or crush method of preparing chromosomes with direct fixation of tissue blocks in 50% acetic acid, often resulted in few high quality metaphase spreads for analysis. These new molecular techniques when introduced into fisheries creates a revolution as there were a lot of things still to be learnt in this field.