Zebrafish Novel Tank Diving Test

The novel tank diving test exploits the innate geotactic response of zebrafish (Danio rerio) when introduced to an unfamiliar environment. Adult zebrafish placed in a novel trapezoidal or rectangular tank initially dive to the bottom third and remain there, a behavior mediated by the habenula-interpeduncular nucleus axis and modulated by serotonergic and GABAergic signaling in the dorsal pallium, the teleost homologue of the mammalian hippocampal-amygdala circuit. Over a standard 6-minute observation window, non-anxious fish gradually explore upper zones, while anxious fish maintain bottom-dwelling with elevated erratic movements and freezing bouts.

The primary dependent variable is the proportion of time spent in the bottom third of the tank, with the water column virtually divided into three equal horizontal zones (bottom, middle, top). Additional measures include latency to first upper-zone entry, number of transitions between zones, total distance traveled, mean swimming velocity, erratic movement episodes (sharp >90-degree turns at high velocity), and freezing events defined as cessation of movement for more than two seconds. Within-session habituation curves plotting bottom-time per one-minute bin reveal the temporal dynamics of anxiety reduction.

ConductMaze segments the tank into user-defined horizontal zones using overhead or side-mounted camera tracking, automatically computing zone occupancy, transition counts, and locomotor metrics at 30 fps. The system generates per-minute time-course plots of vertical position, erratic movement frequency histograms, and freezing event timelines. Batch processing supports simultaneous multi-tank configurations for high-throughput anxiolytic screening across pharmacological treatment groups.