Poecilia latipinna sailfish molly was exposed to diclofenac (DCF) at concentrations of 0 (control), 0.5, and 1.0 mg/L for 14 days with changing the water in which the DCF was daily dissolved during the experimental period. Morphology abnormalities in the jaws and spine, as well as erosion of the dorsal and caudal fins, were noted in the treated fish. Gene expression analysis showed a decrease in col1α1 gene expression in treated fish with diclofenac. The col1α1 fold change, for the analysis of fish with a total length of 20mm (0, 0.5 and 1.0mg/L), recorded values of 133± (0.04 a), 0.75 ± (0.01b), and 0.53± (0.01c), respectively. This showed a significant value (P<0.01), in comparison with the control group. For the adult fish, fold change of col1α1 showed values of 1.38± (0.24 a), 0.83± (0.18 ab), and 0.47± (0.09 b) for the treatments 0, 0.5, and 1.0 mg/L, respectively, showing a significant decrease (P<0.05) in comparison with the control, although there was no significant difference between the diclofenac treatment at the concentration of 0.5 mg/L and the control treatment. In addition, the gene expression of female fish decreased significantly (P<0.05) through the treatments of 0.5 and 1.0 mg/L, compared to the control. Whole-mount of Alizarin and Alcian staining were used to discover the deformation of the skeleton showing the effect of DCF on bone remodeling in vertebrae, ribs between bones, cartilage, and the fins of fish.