摘要：ABSTRACT Increasing of freshwater tambaqui Colossoma macropomum demand makes the farmers increase the production of the consumption fish and seed. Acceleration of the production cycle can increase total production level, and reduce the level of osmotic work can be used to improve fish growth. This study aimed to analyze the effect of the addition of calcium carbonate (CaCO 3 ) in the saline medium of 3 g/L on the growth of freshwater tambaqui juvenile. Tambaqui used has a body length of 1.93 ± 0.1 cm and weight of 0.26 ± 0.03 g. The experiment used 15 units of aquarium at size of 30×15×25 cm 3 and filled with 9 L of saline water, then added lime CaCO 3 according to treatment. The treatments were control (0 mg/L CaCO 3 ), A (50 mg/L CaCO 3 ), B (100 mg/L CaCO 3 ), C (150 mg/L CaCO 3 ), and D (200 mg/L CaCO 3 ). The study was conducted for 30 days of maintenance. Fishes were fed on bloodworms ad libitum or provided three times a day. The results showed that survival, daily growth rate, and absolute length growth of the CaCO 3 treatments significantly higher (P<0.05) that that of control. Furthermore, survival, daily growth rate, and absolute length growth among the CaCO 3 treatments were the same. Thus, addition CaCO 3 of 50 mg/L saline water of 3 g/L can be applied to increase culture performance of freshwater tambaqui. Keywords: freshwater tambaqui, CaCO 3 , salinity ABSTRAK Permintaan terhadap ikan bawal air tawar Colossoma macropomum yang semakin meningkat membuat pembudidaya menambah produksi ikan konsumsi dan benih. Percepatan siklus produksi dapat meningkatkan total produksi budidaya, dan energi dari optimasi kerja osmotik dapat dialokasikan untuk pertumbuhan. Penelitian ini bertujuan untuk menganalisis pengaruh penambahan kalsium karbonat (CaCO 3 ) pada media bersalinitas terhadap pertumbuhan benih ikan bawal air tawar. Benih ikan bawal yang digunakan memiliki panjang 1,93±0,1 cm dengan bobot 0,26±0,03 g. Akuarium yang digunakan berukuran 30×15×25 cm 3 sebanyak 15 unit dan diisi air bersalinitas 3 g/L sebanyak 9 L, kemudian ditambahkan kapur CaCO 3 sesuai perlakuan. Dosis setiap perlakuan terdiri atas kontrol (0 mg/L CaCO 3 ), A (50 mg/L CaCO 3 ), B (100 mg/L CaCO 3 ), C (150 mg/L CaCO 3 ), dan D (200 mg/L CaCO 3 ). Penelitian dilakukan selama 30 hari pemeliharaan dengan pemberian pakan cacing sutra secara ad libitum atau diberikan tiga kali sehari. Hasil penelitian menunjukkan bahwa derajat kelangsungan hidup, laju pertumbuhan harian, dan panjang mutlak pada perlakuan penambahan kapur CaCO 3 lebih tinggi (P<0,05) daripada kontrol. Sementara itu, derajat kelangsungan hidup, laju pertumbuhan harian, dan panjang mutlak antarperlakuan penambahan kapur CaCO 3 tidak berbeda. Dengan demikian, penambahan CaCO 3 sebanyak 50 mg/L air dapat diterapkan untuk perbaikan performa budidaya ikan. Kata kunci: ikan bawal air tawar, CaCO 3 , salinitas
