Artificial and natural hybridization of dojo
loach Misgurnus anguillicaudatus (2N = 50, DD for
short) and large-scale loach Paramisgurnus dabryanus
(2N = 48, PP for short) are well-grown. However, these
hybrid loaches have not yet been examined for fertility
and ploidy of gametes. Here, histological observations,
artificial propagation, observations of embryonic development,
larval morphology, and ploidy analyses were
conducted to determine the fertility and ploidy of gametes
of allodiploid (DP for short) and allotriploid (DDP
for short) loaches, produced by DD females × PP males
and induced from fertilized eggs of DD females × PP
males by cold shock to prevent the second polar body
release, respectively. The ovaries of DP and DDP included
smaller number of eggs when compared with those of the control DD, while full-grown oocytes were
observed. Testes of these two loaches were delayeddeveloped
without spermatids or mature spermatozoa.
Results obtained here showed that DP and DDP were
fertility-weakened female and sterile male. Moreover,
DP females and DDP females could, respectively, produce
few viable haploid eggs and few viable haploid and
diploid eggs. This study will provide valuable information
for fish hybrid researches.