Comparison of lethal concentrations (LC50 – 96 H) toward common carp, Cyprinus carpio Linnaeus 1758 mortality in leather industry liquid waste and piretroid insecticide

The common carp ( Cyprinus carpio ) with sizes of 3 - 5 cm are usually culture in the paddy fields when the plants still need water for its growth. However, the water which is used to irrigate the paddy fields often contains pollutants, comes from polluted rivers. This study aimed to determine the value of lethal concentrations (Lc 60 –96 H) in the waste water of leather industry and pyrethroid insecticide with Deltametrin active compound toward mortality of common carp seeds. The research was conducted in two different stages and performed in an experimental method with completely ran-domized design. The experiments for liquid waste of leather industry used seven experiments, while for insecticides with eight experiments. The result of probit analysis for waste of leather industry indicated that LC 50 – 96 H was 0,056 ml L -1 , while for pyretroid insecticide was 0.0042 mg L -1 . It could be said that insecticide had stronger effect on fish seeds mortality because only small amount of concentration could kill fish seeds. The results of this study shown that insecticides was ± 70 thousand times easier to kill fish seeds compared with leather industry waste. Therefore, people should be careful when disposing waste into the water because it will disrupt the life of aquatic organism. Abstrak Benih ikan mas ( Cyprinus carpio ) ukuran 3 - 5 cm seringkali dipelihara di sawah yaitu pada saat padi masih membu-tuhkan air untuk pertumbuhannya. Namun air yang digunakan untuk mengairi sawah seringkali mengandung bahan pencemar karena berasal dari sungai yang menerima limbah. Penelitian ini bertujuan untuk mendapatkan nilai LC 50 – 96 jam limbah penyamakan kulit dan insektisida piretroid berbahan aktif deltametrin terhadap mortalitas benih ikan mas. Penelitian ini dilaksanakan dalam dua tahap yang berbeda dan dilakukan dalam metode eksperimen rancangan acak lengkap. Eksperimen untuk limbah cair penyamakan kulit digunakan tujuh perlakuan dan insektisida digunakan delapan perlakuan.  Hasil analisis probit untuk limbah penyamakan kulit diperoleh nilai LC 50 – 96 jam sebesar 277,73  ml L -1 sedangkan nilai LC 50 - 96 jam untuk insektisida piretroid yakni 0,0042 mg L -1 . Hal ini menunjukkan bahwa insektisida lebih kuat pengaruhnya terhadap kematian benih ikan, karena dengan konsentrasi yang sedikit saja sudah dapat mema-tikan benih ikan. Hasil penelitian menunjukkan bahwa insektisida ±70.000 kali lebih mudah mematikan benih ikan dibandingkan dengan limbah penyamakan kulit. Sebab itu, perlu kewaspadaan dalam membuang limbah ke perairan umum karena akan mengganggu kehidupan organisme penghuninya