Prevalence study of gill parasites of sillaginid fish from the upper Gulf of Thailand and new host records

Abstract

Ectoparasite surveys were undertaken on 228 sillaginid fish samples from the upper Gulf of Thailand during February 2016–February 2017. Six sillaginid fish species were identified: Sillago aeolus, S. asiatica, S. indica, S. ingenuua, S. maculata and S. sihama. S. indica was observed in the highest number, while S. maculata was observed in the lowest number. This report is the first to describe S. indica in the Gulf of Thailand. All the sillaginid fish samples were examined for gill parasites. Eight species of gill parasites were identified: three species of monogenean (Paradiplectanum blairense, P.sillagonum and Monoplectanum australe) and five species of copepods (Nothobomolochus lateolabracis, Lernanthropus sillaginis, Caligus epinepheli, Caligus sp. and Branchiella sp.) Paradiplectanum spp. and Lernanthropus sillaginis were found in all samples. Paradiplectanum blairense and P. sillagonum were parasitized with S. indica, S. sihama and S. ingenuua; Monoplectanum australe was found in S. aeolus and S. maculata; Nothobomolochus lateolabracis was found in S. indica and S. sihama; Branchiella sp. was found in S. indica; and Caligus epinepheli was found in S. sihama. Three new host records were found: Monoplectanum australe was found in S. aeolus, while Paradiplectanum blairense and P. sillagonum were found for the first time in S. ingenuua. This report is the first to identify M. australe, N. lateolabrachis and C. epinepheli in the upper Gulf of Thailand.