ABSTRACT
Rainbow trout is the most extensively cultured salmonid species and artificial populations can be found worldwide, except for Antarctica. Easily adapted to captivity conditions, rainbow trout is one of the oldest cultured fish for human food supply, just behind the common carp. In April, 1949, the salmonid introduction process was restarted by the Agriculture Ministery, and nearly 5.000 eyed eggs of rainbow trouts were imported from Esbjerg, Denmark. Prior to this procedure, limnological studies in Mountain Rivers on Southeastern Brazil were carried out by Ascanio de Faria. New and successive rainbow trout introductions were carried out right from 1962, when 200,000 eyed-eggs were imported from California. Analysis of chromosomes from rainbow trout firstly revealed the Nucleolar Organizer Regions located at subterminal position on the short arms in a pair of submetacentric chromosomes in individuals of both wild and cultured stocks.
