The pollution of aquatic ecosystems by crude oil poses a serious challenge to aquatic life. This study aimed to investigate the effects of microalgae fed with soluble crude oil on the growth, survival, egg production, nauplii, and fecal pellets of copepods. Heavy crude oil from Iran was used as the pollution source and mixed with deionized water to produce water-soluble fraction (WSF) concentrations. This mixture was stirred for 24 hours at 25 °C in the dark and then filtered. The experimental treatments included concentrations of 0.2, 0.5, 1, and 2 grams per liter of crude oil, along with a control group. Copepods were collected from the Persian Gulf ecosystem and maintained under laboratory conditions. For feeding these organisms, Nannochloropsis algae were cultivated in an F/2 growth medium. The experimental design was divided into two main phases: in the first phase, the effects of crude oil on algal growth were investigated, and in the second phase, the impact of contaminated algae on copepods was assessed. The experiments were conducted randomly using a completely randomized design (CRD). The results showed that the addition of soluble crude oil in water significantly reduced algal growth in the first 24 hours compared to the control group. However, as time progressed, the growth trend changed, with the highest algal growth observed at 0.5 grams per liter on day 3 (49.32%), 0.25 grams per liter on day 4 (47.73%), 1 gram per liter on day 5 (38.55%), and 2 grams per liter on day 7 (36.43%). Regarding the survival percentage of copepods, the results indicated that at 24 hours, the highest survival rate was in the control and 0.25 grams per liter treatment (94%), while the lowest was in the 2 grams per liter treatment (13%). The control group consistently exhibited the highest survival percentage at 48, 72, and 96 hours, while the 2 grams per liter treatment showed the lowest. The number of fecal pellets produced by copepods was also assessed at 24 and 48 hours. A