Assessment of the Scales of Gilthead Seabream (Sparus aurata L.) by Image Analysis and Atomic Force Microscopy

Understanding the protective role of fish skin is critical to improving the development of aquaculture, since skin is the main surface that separates the animal from its always hazardous environment. Many techniques have been used for its study, but certain structural characteristics of fish skin still remain not clearly understood. That is the case with scales, which have always been attributed a mere protective role, but which are proving to have more functions than it was traditionally thought. To acquire a deeper knowledge, scales from six different regions of gilthead seabream (Sparus aurata L.) were studied and measured by image analysis. Results prove that scales from the base of the dorsal fin are larger than those in other parts of the fish body while scales from the peduncle are the smallest of the skin. Furthermore, a technique relatively new in this field, known as atomic force microscopy (AFM), was used to obtain representations of the ultrastructure of the scales and measure certain features such as the circuli and the lines in the basal layer. The data obtained allowed us to compare the height of circuli among the different scales, showing that they were higher in scales from the dorsum and the operculum. The present results introduce a nanostructural model of the scales of gilthead seabream that might serve as a useful guideline for future studies.