The dosage of gentamicin for lateral line ablation varies among fishes

The lateral line is a mechanosensory system that plays an important role in key fish behaviors such as navigation, prey detection, and schooling. To study the role of the lateral line in these behaviors, researchers often ablate it using aminoglycoside antibiotics such as gentamicin, which are cytotoxic to the sensory hair cells in the lateral line. However, such drugs have proven challenging to work with as the dose required to fully ablate the lateral line varies from species to species. To identify effective gentamicin concentrations for five commonly studied fish species, we treated zebrafish (Danio rerio), giant danios (Devario aequipinnatus), cherry barbs (Rohanella titteya), neon tetras (Paracheirodon innesi), and black neon tetras (Hyphessobrycon herbertaxelrodi) with increasing concentrations of gentamicin (0.001–0.003%) and visualized neuromasts using fluorescent vital dye staining. We found that required doses varied considerably across species: danionids and black neon tetras were fully ablated at 0.001%, cherry barbs required 0.002%, and neon tetras required the highest dose of 0.003%. While we cannot currently determine the biological reasons for differences in gentamicin sensitivity, we suggest hypotheses for future work relating to lateral line morphology, evolutionary relatedness, habitat, and cellular mechanisms. We recommend that researchers test gentamicin doses on each new species before beginning lateral line experiments to ensure full ablation is achieved.