Use of a Split Depth and Visual Cliff Apparatus to Measure the Diving Response in Zebrafish

The open tank diving test and the light/dark test are commonly used to assess anxiety-like behavior in zebrafish. The open tank test exerts relatively weak control over behavior, and uses vertical locomotion as its primary measure. The light/dark test exerts relatively strong control over behavior, and uses horizontal locomotion as its primary measure. Although both are used to measure anxiety-like behavior, current pharmacological evidence suggests that behavior in the two tests may reflect distinct neurological mechanisms (1). We outline here the use of a split depth apparatus, which measures the diving construct central to the open tank, but produces the relatively low behavioral variance observed in the light/dark test. The apparatus can be flexibly modified to strengthen or weaken baseline preference, and can measure preference for depth even when the animal cannot dive. We recommend this test as an alternative to the standard open tank when excessive behavioral variability is undesirable, when recording from above is necessary, or when vertical locomotion may be impaired.