NiCl2-induced developmental malformations. Examples are shown of zebrafish larval malformations present at 5 dpf, following exposure to NiCl₂ (50 mg Ni/L) for 4 days. A. Control, healthy zebrafish with normal morphology, including swim bladder (SB) formation. B. Zebrafish with abnormal spinal curvature including kyphotic (Ky) and lordotic (Lo) deformities. C. Zebrafish with more prominent lordosis (Lo) and pericardial edema (PE) D. Zebrafish with severe lordosis (Lo), pericardial edema (PE) abdominal edema (AE), tissue necrosis (TN), abnormal fin morphology (FM) and small eyes (E). Note panels B-D show failure of swim bladder formation; C and D also show shortened body length. C also shows lateral spinal curvature (scoliosis) seen as the caudal extremity of the body being out of the plane of focus of the micrograph.