Performance of the Progeny of Natural Tetraploid Loaches in Long-Term Communal Rearing Experiments under a Laboratory Condition

摘要

In the loach Misgurnus anguillicaudatus, triploid (3n) and tetraploid (4n) individuals were produced by crosses using diploid (2n) gametes of natural tetraploids, which had been found in the specimens obtained from fish dealers. Long-term communal rearing experiments from the age of 1 month old to 3 years 1 month old were carried out among diploid (2n female x 2n male), triploid (4n x 2n) and tetraploid (4n x 4n) to compare their performance under a laboratory condition. At the end of experiments, significantly retarded growth was observed in tetraploids and they showed significantly lower body length/head length proportion than diploid and triploid individuals. Triploid females exhibited less developed gonad than tetraploid and diploid individuals,when compared gonad somatic index (GSI). Triploid and tetraploid males showed lower GSI than diploid males, but tetraploid males gave better gonadal development than triploid males.