A Simple and Precise Feed-Based Approach to Oral Drug Delivery in Fish

Typical methods for drug delivery in fish (e.g., beaker dosing, intraperitoneal injections, or oral gavage) are time-consuming, imprecise, and/or wasteful. Because these methods are also stressful for the animals, they are poorly suited for repeated or long-term drug administration and behavioral experiments that are sensitive to handling-related confounds, thereby limiting the utility of fish models in biomedical research. To overcome these obstacles, a gelatin-based feeding method was developed to enable rapid, precise drug dosing in fish with minimal disturbance. The method involves preparing individually tailored morsels of feed composed of gelatin, brine shrimp extract, spirulina, and the drug of choice. The heat malleable properties of gelatin allow a single homogeneous preparation to be liquefied, accurately portioned according to individual body mass, and re-solidified into customized morsels. As proof of principle, the NMDA receptor antagonist MK-801 (4 mg kg⁻¹) was administered to adult zebrafish prior to the novel tank test, resulting in behavioral effects consistent with reduced anxiety-like behavior. This approach is well suited for behavioral pharmacology and is readily adaptable to other aquatic model organisms.