Sumberdaya kelautan dan perikanan merupakan salah satu kekayaan alam yang dimiliki Indonesia, kepiting bakau (Scylla serata) adalah salah satu sumberdaya perikanan bernilai ekonomis tinggi dan potensial untuk dibudidayakan, akan tetapi keberhasilan suatu usaha penggemukan kepiting bakau tidak terlepas dari masalah penyakit dan parasit. Salah satu parasit yang sering menyerang biota budidaya ialah parasit Chilodonella sp. Pada insang kepiting bakau (Scylla serrata) diperairan Kota Tarakan. Penelitian ini bertujuan untuk mengetahui prevalensi distribusi Chilodonella sp., pada insang kepiting bakau (Scylla serrata) di perairan kota Tarakan. Metode yang digunakan ialah purposive sampling dan identifikasi parasit menggunakan Mikroskop trinoculer. Penelitian ini dilaksanakan kurang lebih 3 (tiga) bulan dengan pengambilan sampel di 4 (empat) titik lokasi sampling berbeda. Berdasarkan hasil penelitian menunjukkan prevalensi Chilodonella sp., tertinggi terdapat di Stasiun IV (Tarakan Timur) 77% dan terendah di Stasiun I (Tarakan Utara) 22%. Prevalensi tersebut memiliki hubungan yang sangat kuat dengan keseluruhan stasiun dengan nilai r² = 0,979 sehingga perlunya perhatian stakeholder terkait terhadap kondisi kawasan pesisir kota Tarakan agar terjaganya kelestarian lingkungan perairan.
Kata Kunci: Scylla serrata., Chilodonella sp., Prevalensi

Marine and fishery resource is one of nature wealth which is had by Indonesia. Mud Crab (Scylla serrata) is one of fishery resources which has a valuable high economy and potential to be cultivated, but the success of one effort in fattening mud crab is not apart from disease and parasite. One of Parasites which always attacks cultivation biota is parasite Chilodonella sp in fish gills of the mud crab (Scylla serrata) at Tarakan City. The used method in this research was Purposive sampling and parasite identification by using Trinocular Microscope. This research was conducted approximately 3 months by taking sample on the four different sampling location points. Based on the results of this research, it was showed that the highest prevalence of Chilodonella sp., was found in Station IV (East Tarakan) 77% and the lowest prevalence was found in Station I (North Tarakan) 22%. The prevalence has a strong relation with all station by estimation r² = 0,979, So that, it needs an attention from stakeholder relates to the condition of Tarakan’s coastal area in order to maintain the conservation of the marine environment. Keywords: Scylla serrata., Chilodonella sp., Prevalence