Effect of Clearing and Staining on Fish Length

Abstract

Our objective was to determine whether the process of clearing and staining for bone and cartilage has a significant effect on fish length. Repeated-length measurements were made on individual specimens (n = 611) of laboratory-reared Tilapia mossambica (5.9-61.5 mm) while live, after formalin fixation and ethanol storage (2 treatments: 2 days and 30 days), and finally after clearing and staining. Our results demonstrate that clearing and staining causes significant shrinkage (3-6%). In contrast to previous studies showing that small specimens shrink relatively more than larger ones when fixed in formalin or ethanol, we found that larger fish shrink relatively more than smaller ones when subsequently cleared and stained. We provide regression equations to convert cleared-and-stained lengths to live or ethanol lengths.