Androgenesis is a technique which involves the production of individuals with all their chromosomes
from the male parent. It can be useful in generating homozygous lines of fish and in the
recovery of genotypes from cryopreserved sperm. However, the survival of androgenetic diploid
fish is typically very low; this may be due to the homozygosity of these individuals or to the
treatments (egg irradiation, suppression of first cleavage) used in generating them. In this study,
we produced androgenetic diploid rainbow trout using (1) normal (haploid) sperm and suppression
of the first cleavage, and (2) sperm from tetraploid males. Survival of the androgenetic diploids
generated using sperm from tetraploid males was much better than that of androgenetic
diploids produced using haploid sperm, suggesting that egg irradiation is not an overwhelming
problem in androgenesis and that cleavage suppression treatments and/or homozygosity may be
responsible for their poor viability. We also generated viable androgenetic diploids usingcryopreserved
sperm from tetraploid males; this technique may be useful for gene banking.