The present study aims to evaluate the viability of reciprocal crosses between Caspian trout (Salmo caspius) and rainbow trout (Oncorhynchus mykiss), and the effect of triploidization on embryonic development, growth and survival of hybrid embryos and larvae. This experiment included six groups of crosses: (1) pure O. mykiss (2nR); (2) pure S. caspius (2nC); (3) diploid and (4) triploid ♀O. mykiss×♂S. caspius hybrids (2nR × C and 3nR × C); (5) diploid and (6) triploid ♀S. caspius×♂O. mykiss hybrids (2nC × R and 3nC × R). Triploidy was induced by a thermal shock after fertilization. Fertilization, hatching, and embryonic development were studied. Hatching rate was more than 90% in 2nR and 2nC, 35% in 2nR × C group, 45% in 3nR × C group, whereas all embryos died before the eyed stage in 2nC × R and 3nC × R groups. Chromosome number ranged between 57 and 61 and 78–81 in 2nR and 2nC groups, 69–71 in 2nR × C and 99–103 in 3nR × C. The time before blastopore closure was the most important point in the embryonic phases when most deaths occurred in all groups. Hatching occurred earlier in 2nR and 3nR × C groups than in 2nC group. The highest final weight and specific growth rate were observed in 2nR and 3nR × C groups. We have demonstrated that triploidy induction can increase the survival rate of distant hybrid (♀O. mykiss×♂S. caspius) and identified the key embryonic stages that could help introduce this hybrid into aquaculture. The hybrid could be easily commercialized if they show significant improvement in growth, survival and disease resistance.

本研究旨在评估里海鳟鱼（Salmo caspius）和虹鳟鱼（Oncorhynchus mykiss）之间互交的可行性，以及三倍化对胚胎发育、杂交胚胎和幼鱼生长和存活的影响。本实验包括六组杂交：（1）纯O.mykiss（2nR）；(2) 纯的卡斯皮乌斯 (S. caspius) (2nC)；(3) 二倍体和 (4) 三倍体 ♀ O. mykiss ×♂ S. caspius杂种（2nR × C 和 3nR × C）；(5) 二倍体和 (6) 三倍体 ♀ S. caspius ×♂ O. mykiss杂交体（2nC × R 和 3nC × R）。三倍体是通过受精后的热冲击诱导的。研究了受精、孵化和胚胎发育。2nR和2nC组孵化率均大于90%，2nR×C组孵化率为35%，3nR×C组孵化率为45%，而2nC×R和3nC×R组胚胎在成眼期前全部死亡。2nR 和 2nC 组的染色体数目范围为 57 至 61 和 78-81，2nR × C 组的染色体数目为 69-71，3nR × C 组的染色体数目范围为 99-103。胚泡关闭前的时间是胚胎期中最重要的时间点，此时死亡最多。所有组均发生。2nR 和 3nR × C 组的孵化发生早于 2nC 组。2nR 和 3nR × C 组的最终重量和特定生长率最高。我们已经证明三倍体诱导可以提高远缘杂交种（♀ O. mykiss ×♂ S. caspius ）的存活率，并确定了有助于将该杂交种引入水产养殖的关键胚胎阶段。如果这种杂交种在生长、存活和抗病性方面表现出显着改善，那么它们就很容易商业化。