This research was carried out to determine the intraocular pressure values, optimum anesthesia dose and phenotypic characteristics in Oscar fish (Astronotus ocellatus). A total of 11 adult, male Oscar fish were used in the study. Optimum anesthesia dose, pre-and post-anesthesia intraocular pressure values and phenotypic measurements (total length, fork length, standard length, dorsal fin base length, head length, body length, eye diameter, body depth, pectoral length, pelvic fin bottom length, anal fin bottom length) were determined and reference values specific to this fish species were obtained by performing a statistical analysis. When exposed to 3 cc/L of the concentrations, fish achieved a deep state of anesthesia (induction time 1.31 min; recovery time 6.42 min). The most balanced anesthesia without risking vital functions was achieved using Clove oil with a dose of 2.5 cc/L. Compared to the other dimensions, total length, fork length and standard length were the most consistent body measurements with high positive correlations. No statistically significant difference (p > 0.05) was seen in both eyes between the intraocular pressure values before (5.36-5.86) and after (5.59-5.36) anesthesia. It is recommended that the ideal concentration of clove oil was 2.5 cc/L to reduce stress and injury damage during handling procedures. Additionally, intraocular pressure values, body measurements and Clove oil optimum anesthesia dose obtained in this study can be used as reference values for Oscar fish raised in aquarium conditions.