Hair cell survival in wild-type *AB zebrafish at 5–7 dpf treated with aminoglycosides (AGs). (A) Twenty-four-hour treatment with gentamicin (1–200 μM) or amikacin (100–1500 μM) or one-hour treatment with neomycin (50–200 μM). (B) Treatment with varying doses of ORC-13661 (0.10–8.3 μM) with 50 μM gentamicin, 200 μM neomycin, or 1000 μM amikacin. Counts from controls without any ORC-13661 are also shown. Means were calculated from α parvalbumin–positive hair cell counts from 4 neuromasts/fish (SO1, SO2, O1, and OC1) after treatment, with 9–11 fish/treatment group. Percentages reflect the average number of hair cells remaining in treated fish, relative to hair cells remaining in vehicle control fish. Vertical arrows in A show LD50 for each of the AGs tested; vertical arrows in B show HC50 for ORC-13661 in the presence of AGs. Error bars represent SD. ORC-13661 protects against toxicity from all 3 AGs in a dose-dependent manner.