The experiment was carried out to determine the potential of deltamethrin active ingredient to cause gill covers flared up in black tiger shrimp (Penaeus monodon) and white leg shrimp (Litopenaeus vannamei). Experimental shrimps with an average body weight of 2.15 ± 0.31 g/individual were set up with 5 treatments (in triplicate) at deltamethrin concentrations of 5%, 10%, 15%, 20% and 25% LC 50 . Resuts showed that shimps death started from day 3 after adding deltamethrin to the experimental

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... s. Shrimps exposed to deltamethrin concentrations 5%, 10% and 15% LC 50 had lower mortality than those exposed to of 20% and 25% LC 50 and displayed gill covers flared up. Histopathological analysis showed that shrimp with gill covers flared up had healthy gill (no deformation on primary and secondary gill filaments) and hepatopancreas (no changes in the structure of the hepatopancreas).