| dc.description.abstract |
Disease and parasite outbreaks cause mortality of
fi
sh, affecting mostly early stages of
fi
sh cycle. The
outbreaks are usually prevented using a number of chemicals including salt (NaCl) for which protocols are
lacking. The purpose of this study was to determine the ef
fi
cacy of NaCl as a potential prophylactic treatment
and its short term toxicity on African cat
fi
sh (
Clarias gariepinus
) yolk-sac and swim-up fry during a 24 h
exposure period. Three-day-old yolk sac and six-day-old swim-up fry (
n
=50 for each stage) were subjected
to static bath dip treatment in increasing concentrations of NaCl (0.1, 0.2, 0.4, 0.8, 1.0, 2.0, 4.0, and 10.0 g/L) for
15, 30 and 60 min. Toxic ranges were tested by exposing the fry stages to concentrations of 0.25, 0.5, 0.75, 1.0,
1.25, and 1.50 g/L NaCl for 24 h. Controls were not subjected to any concentration of NaCl. All experiments
were executed in triplicate. Regardless of the concentrations and duration of exposure, survival of
fi
sh in NaCl
treatment differed signi
fi
cantly (
P
b
0.05) from the untreated controls. Effective concentration ranges of NaCl
were 0.2
–
0.8 g/L and 0.2
–
1.0 g/L in the yolk sac and swim-up fry respectively at exposure duration of 15 min.
No fry survival was recorded at a concentration of 10.0 g/L for either stage of development. The mean 24 h
LC
50
values for the yolk sac and swim-up fry were 0.61 and 0.70 g/L NaCl respectively. Sodium chloride may be
used as prophylactic treatment in early stages of
C. gariepinus
but could be toxic at longer exposure times.
However, empirical tests on ef
fi
cacy of NaCl on pathogens are recommended |
en_US |