SUCCESSFUL PROPAGATION IN SEAWATER OF THE GUPPY POECILIA-RETICULATA WITH REFERENCE TO HIGH SALINITY TOLERANCE AT BIRTH

Seawater tolerance of newborn guppies was measured by way of survival rates 24 h after transfer to seawater. The newborn guppies showed high seawater tolerance and some of them survived in 35 ppt seawater. Seaw ater tolerance significantly decreased within 5 days after birth and t hen became stable at a level comparable to adults. After a challenge t est with 35 ppt seawater at birth, the surviving individuals remained alive more days and grew in 35 ppt seawater. They yielded offspring, a nd most of their progeny survived in 35 ppt seawater. Therefore, the g uppies could propagate in seawater and a seawater-tolerant strain was established.