We are currently experiencing rapid growth in pollutants defiling our freshwater environment. The main contributors to the disruption are anthropogenic activities, such as agriculture and city pest control, increasing the amount of chemical contamination. This includes pesticides (more aptly called biocides) that contribute to stressors debasing aquatic ecosystems. Heat stress (through global climate change, heat waves, or natural seasonal variation) also negatively influences the behavior of aquatic animals. In this study, we examined dose-dependent and time-dependent effects of pesticide cocktail (metalachlor, linuron, isoproturon, tebucanazole, aclonifen, atrazine, pendimethalin, and azinphos-methyl) and heat stress (32°C for 1-month exposure) on the free-swimming behavior and cumulative actionless time (resting time) of goldfish (Carassius auratus, a model teleost species). Behavioral analysis showed an inverse relationship between distance swam and cumulative actionless time, with a dose-dependent, time-dependent, decrease in distance swam as well as a dose-dependent, time-dependent increase in cumulative actionless time. Collectively, these results indicate that the combined effects of heat and pesticide stress alter behavior and negatively impact natural swimming patterns in teleost species, such as Carassius auratus.