Kota tarakan terkenal dengan industri perikanan seperti industri cold storage udang yang pada umumnya menghasilkan limbah cair organik dengan karakteristik nilai ph rendah, chemical oxygen demand (cod), biological oxygen demand (bod), dissolved oxygen (do), protein dan lemak yang tinggi, sehingga jika dibuang langsung ke badan air dapat mencemari lingkungan perairan dan berdampak buruk bagi biota perairan. tujuan penelitian ini adalah untuk nilai toksisitas akut lc50-96 jam limbah cair cold storage udang terhadap ikan bandeng. metode penelitian menggunakan eksperimetal berupa uji hayati secara statis dalam waktu 96 jam menggunakan ikan bandeng sebagai hewan uji dengan mengambil sampel air limbah pada inlet dan outlet cold storage udang. tahapan penelitian terdiri dari tahap uji kualitas air limbah dengan parameter (ph, suhu, do, cod, dan bod), tahap pemeliharaan, tahap aklimatisasi, uji pendahuluan dan uji toksisitas. uji toksisitas dilakukan dengan memberikan perlakuan pada media uji dengan konsentrasi limbah cair yaitu 0 ml/l, 460 ml/l. 775 ml/l, 1000 ml/l, 1225 ml/l, dan 1450 ml/l. nilai toksisitas akut diperoleh dengan dengan metode epa probit yang dianalisis dengan pendekatan regresi linier. hasil analisis regresi linier menunjukkan bahwa konsentrasi limbah cair memiliki pengaruh terhadap mortalitas ikan bandeng dengan nilai r = 0,9178 pada limbah inlet dan nilai r = 0,978 pada limbah outlet. nilai toksisitas limbah cair cold storage udang terhadap ikan bandeng memiliki pengaruh yang signifikan, karena semakin tinggi konsentrasi limbah cair cold storage maka semakin tinggi tingkat mortalitas ikan bandeng. berdasarkan pendekatan nilai probit diperoleh nilai lc50-96 jam pada limbah inlet sebesar 251 ml/l sedangkan pada limbah outlet sebesar 501 ml/l. kata kunci: cold storage, ikan bandeng, limbah cair, toksisitas

Tarakan city is famous for its fishing industry, such as the industry of cold storage shrimp which generally produces organic liquid waste with the value characteristics of low ph, chemical oxygen demand (cod), biological oxygen demand (bod). dissolved oxygen (do), high protein and fat. therefore, if it is directly thrown away into the water, it can pollute the aquatic environment and have negative impact on aquatic biota. the purpose of the research was to analyze the value of acute toxicity test of lc50-96 hours liquid waste of cold storage shrimp towards milkfish. the research method used experimental in the form of a statistic biological test for 96 hours. it used milkfish as animal test and used the water waste in the inlet and the outlet of cold storage shrimp as the sample. the phases of research consisted of testing the quality of water waste with the parameters (ph, temperature, do, cod, and bod), maintenance phase, acclimatization phase, preliminary test and toxicity test. the toxicity test was carried out by giving treatment to the test media with the concentration of liquid waste of 0 ppm, ppm, 775 1000 ppm, 1225 ppm, and 1450 ppm. the value of acute toxicity was obtained using the epa probit method that was analyzed using a linear regression approach. the results of linear regression analysis showed that the concentration of liquid waste had an effect on milkfish mortality with the value of r=0.9178 in the inlet waste and the value of r 0.978 in the outlet waste. the toxicity value of liquid waste of cold storage shrimp had a significant effect because the higher of liquid waste concentration of cold storage, the higher of mortality rate of milkfish. based on the probit value approach in the value of lc50-96 hours was obtained 251 ml/l for the inlet waste and 501 ml/l for the outlet waste. keywords: cold storage, milkfish, liquid waste, toxicity