A high-throughput test of anxiety for zebrafish (Danio rerio) larvae: the larval diving response (LDR)

Background: Zebrafish are used in anxiety research as the species' naturalistic diving response to a new environment is a reliable and validated marker for anxiety-like behavior. One of the benefits of using zebrafish is the potential for high throughput drug screens in fish at the larval stage. However, at present, tests of anxiety in larvae and adults often measure different endpoints. New Method: Here, for the first time, we have adapted the novel tank diving response test for examining diving behavior in zebrafish larvae to assess anxiety-like behaviors at very early-stages (7 days-post-fertilization [dpf]). Comparison with Existing Methods: Current methods to examine anxiety in larvae can show low reliability, and measure different endpoints as in adults, thus calling into question their translational relevance. Results: We found that 7dpf zebrafish spent more time at the bottom of a small novel tank. We validated this as anxiety-like behaviors with diazepam reducing, and caffeine increasing the time spent in the bottom of the novel environment. Conclusions: This new automated and high-throughput screening tool has the potential use for screening anxiogenic and anxiolytic compounds, and for studies aiming to understand the mechanisms underlying affective disorders. ### Competing Interest Statement The authors have declared no competing interest.