Fishermen who inject drugs represent an understudied group at high risk for HIV in Malaysia. This study describes fishing, drug use, and attitudes toward medication-assisted treatment (MAT) for opioid use disorders. Thirty-four male ethnic Malay fishermen completed semistructured interviews analyzed by content analysis. Analysis revealed four themes surrounding opioids, which they called ubat ("medicine"): (a) the fishing lifestyle facilitating substance use, (b) previous unsuccessful attempts to quit, (c) categorizing substances as haram or halal, and (d) attitudes toward MAT. Fishermen's environment permits substance use, including injecting drugs on boats. Fishermen expressed more positive attitudes toward methadone and negative attitudes toward buprenorphine.