Validation of the in-house designed one-trial inhibitory avoidance test for two strains of adult zebrafish

Open-source validated tools are important for affordable high-quality science. Zebrafish model is often used in behavioral sciences, thus validated tools must be developed for this species. We aimed to implement the memory task one-trial inhibitory avoidance test in our laboratory by creating a custom-built 3D printed apparatus and custom-made hardware and software using microcontrollers; this decreases the costs and increases methodological flexibility. In this task, a mild electric shock (3.3 {+/-} 0.3V and 2A for 5sec) is used as an aversive stimulus for the one-trial inhibitory avoidance task based on classical conditioning. For this study we used 72-adult zebrafish from the AB and TU strain. The aversive stimulus caused a robust and long-lasting memory that was learned in one session. The apparatus consisted in one aquarium with two compartments (white and black) where, during the conditioning session, the shock was delivered in the preferred side (black), followed by 30min of immersion in 20M MK-801, a compound known for inducing amnesia (amnesic group, n= 20 for AB and 17 for TU), or in clean water (control, n= 20 for AB and 15 for TU). Both the AB and TU strain animals from the control group took more time to enter in the black compartment after conditioning (p[≤]0.039), indicating avoidance for the black side, while the latency was not altered in the MK-801 group, demonstrating impaired memory. In summary, this open-source apparatus is an affordable and validated option for memory assessment for the two most used strains of zebrafish in research.