In the loach Misgurnus anguillicaudatus, triploid (diploid femalextetraploid male) females laid both large-sized triploid and small-sized haploid eggs. First-generation triploid gynogens were produced by activating the large-sized eggs with UV-irradiated spermatozoa. Mature 4-year-old gynogens were all females and laid one, two or three types of gametes, simultaneously: large-sized, small-sized and intermediate-sized eggs. Frequencies of such eggs differed among individuals of the first-generation triploid gynogens. When the large-sized eggs were triggered to induce gynogenetic development by UV-irradiated spermatozoa, the resultant second-generation gynogens had triploid DNA content. However, the gynogens induced from the intermediate-sized eggs exhibited aneuploid (1.4-1.5n) chromosome numbers and karyotypes. Gynogens from the small-sized eggs died before feeding, probably due to the expression of haploid syndrome. Among the second-generation triploid gynogens, some individuals revealed DNA fingerprints identical to the mother, but others gave patterns slightly different from the mother when the samples were digested with HinfI and then hybridized with oligonucleotide probes (GACA) 4 , (GGAT) 4 and 33.15. These results showed that both clonal and aclonal unreduced eggs might be formed in the triploid gynogens.