INTENSITAS PARASIT INSANG (TREMATODA MONOGENEA: Pseudorhabdosynochus sp.) PADA IKAN KERAPU HIBRIDA MELALUI INFEKSI BUATAN

Infeksi trematoda monogenea: Pseudorhabdosynochus sp. dapat menyebabkan kematian massal pada ikan kerapu. Prevalensi infeksi trematoda ini mencapai 100%, namun intensitasnya hingga menimbulkan gejala klinis dan kematian ikan belum diketahui. Tujuan dari penelitian ini adalah untuk mengetahui intensitas parasit insang (Pseudorhabdosynochus sp.) pada ikan kerapu hibrida “cantik” melalui infeksi buatan. Ikan uji direndam dalam air tawar dengan 100 mg/L formalin selama satu jam sebelum digunakan. Infeksi buatan dilakukan melalui (A) kohabitasi antara ikan sehat dengan ikan sakit dan (B) penempelan potongan lamella insang ikan yang terinfeksi parasit ke lamella insang ikan sehat. Pada perlakuan (A) sebanyak lima ekor ikan uji dipelihara bersama dengan dua ekor ikan sakit selama 3-4 hari, sedangkan perlakuan (B) penempelan lamella insang ikan sakit (1 g lamella insang/ikan) dilakukan pada lima ekor ikan uji selama lima menit. Masing-masing perlakuan diulang tiga kali. Pada Kontrol kepadatan ikan uji sehat sebanyak enam ekor dan lima ekor. Wadah yang digunakan berupa bak plastik volume 100 L. Pengamatan intensitas parasit dan telurnya pada setiap lamella insang bagian kanan dan kiri dari lima ekor ikan uji dilakukan selama tiga minggu dengan interval waktu satu minggu. Hasil pengamatan menunjukkan bahwa kohabitasi antara ikan sehat dan ikan sakit menyebabkan intensitas parasit Pseudorhabdosynochus sp. dan telurnya lebih tinggi dibandingkan dengan penempelan lamella insang. Pada kontrol, Pseudorhabdosynochus sp. maupun telurnya tidak ditemukan selama tiga minggu pemeliharaan. Hasil ini menunjukkan penyebaran Pseudorhabdosynochus sp. dari ikan sakit ke ikan sehat lebih cepat dibandingkan dengan penempelan dari lamella insang ikan sakit.Monogenetic trematode (Pseudorhabdosynochus sp.) infection often leads to mass mortality in groupers, with prevalency reaching 100%. However, the intensity of this parasite to infect grouper fish has yet to be reported. The purpose of this research was to study the intensity of Pseudorhabdosynochus sp. in hybrid grouper “cantik” through experimental infection. The test fish were soaked with 100 mg/L of formalin in fresh water before used. The experimental infections were performed through: (A) cohabitation between healthy fish with sick fish and (B) infection with attached of gills lamella of sick fish to gill lamella of healthy fish. In treatment (A), a total of five test fish were cohabited with two sick fish for 3-4 days, while in treatment (B), attachment of gills lamella (1 g/fish) was done on five test fish for five minutes. Each treatment was repeated for three times. Six and five test fish were maintened as controls. The containers used were 100 L plastic tanks volume. Observation of intensity of the parasite infection and its egg production in each lamella along the right and left gills of five fish were conducted for three weeks with one week intervals. The result showed that the cohabitation between healthy and sick fish caused an increase in total of Pseudorhabdosynochus sp. and its eggs compared with the attachment of chopped-gills. In the control group, Pseudorhabdosynochus sp. and its eggs were not found for three weeks. These results indicate the spread of Pseudorhabdosynochus sp. from the sick fish to the healthy is fish faster than the attachment of gill lamella from the sick fish.