Prevalence of ectoparasites in milkfish (Chanos chanos) from nursery and rearing ponds

Milkfish (Chanos chanos) cultivation is inseparable from the disease problems caused by viruses, bacteria, fungi, and parasites. Dactylogyrus sp. often affects the heart organ of C. chanos. Young specimens in nursery ponds are more susceptible to the related diseases than adults in enlarged ponds. The current research compared the prevalence of ectoparasites infesting C. chanos in the nursery and rearing ponds, in order to prevent parasite infestation. An experimental study was conducted by using survey methods. Simple random sampling used to select 300 samples from nursery and rearing ponds in 3 different cultivation locations. The main investigated parameter in this study was the prevalence of ectoparasites infesting C. chanos in nursery and rearing ponds. Besides, water quality parameters were also determined, including temperature, salinity, pH, brightness, dissolved oxygen levels, and ammonia. The study identified Dactylogyrus vastator as the ectoparasites that infested C. chanos in the nursery and rearing ponds. The average prevalence of ectoparasites in the nursery pond was of 5.33%, while in the rearing pond it was of 2.0%. The Chi-Square test showed a significance value of 0.293 in both, nursery and rearing ponds. The water quality measurements of both ponds resulted an optimum value in temperature (26-28^oC), salinity (17-20 ppt), brightness (25-28 cm), pH (7-8), and ammonia levels (0.01-0.05 mg L^-1). The D. vastator infestation in C. chanos in the nursery and rearing ponds was at an occasional level and did not show significant differences in the prevalence values between the two ecosystem pools.