Crude oil, hypoxia, or their combination affects adult brain morphology and offspring growth but not social and exploratory behaviors in zebrafish.

Environmental stressors can impact fish populations by altering individuals' behavior and physiology. Exposure in fish to crude oil or hypoxia affects physiological processes and leads to behavioral impairments such as increased anxiety-like behavior and aggression. However, the effects of parental exposure to crude oil and hypoxia on the F1 offspring remain poorly explored. We investigated the growth and brain morphology of parental zebrafish exposed for five weeks to: 1) Control conditions (normoxic water, control diet); 2) Hypoxia (60 % air saturation hypoxic water, control diet); 3) HEWAF (normoxic water, HEWAF-loaded diet); and 4) Hypoxia-HEWAF (60 % air saturation hypoxic water, HEWAF-loaded diet). Adults were bred at 0- and 30-days post exposure (DPE) to determine if potential cross-generational effects "wash in" or "wash out" over time on the growth and behavior of the offspring. Tests of sociability (swimming speed, time to approach, and time spent near conspecifics) and exploration (swimming speed, time to approach novel object) were performed in clean, normoxic water on F1 larvae at 19-20 dpf. The size of the right optic tectum decreased in adult fish dietarily exposed to crude oil. Additionally, larvae from parents exposed to crude oil and hypoxia independently produced offspring that had lower mass and length at 0 DPE, but only the larvae from parents exposed to hypoxia remained smaller at 30 DPE. However, social and exploratory behaviors, as well as swimming speed, were not affected in offspring of any parental oil or hypoxia treatment group. Our results indicate that, despite inheritance of reduced body size, offspring behavior remained unaffected, suggesting that an important aspect of larval fitness is influenced by parental stressor exposure.