Histological Investigation of the Skin Structure in the Common Carp (Cyprinus carpio) and the Catfish (Silurus triostegus): Aquatic Environment Adjustment

The skin is a barrier separating the internal tissues from the outer environments in aquatic animals. It plays a major role in protection, osmoregulation, and sensory perception. Specimens from ten common carp (Cyprinus carpio) and ten catfish (Silurus triostegus) have been used to investigate the histological features of their skin. The histological findings of the current study indicated that there was an appreciable variation in the skin architecture between the two selected species. The skin of common carp was covered with scales that were variable in shape and size, in addition to the presence of a thick epidermal layer, keratinocytes, and several mucous layers. In contrast, a thin epidermis layer and a high density of club cells were found in the catfish skin compared to those in common carp. This variation suggested that the common carp skin is better at protecting against external environmental stressors. In contrast, the higher density of goblet cells in the skin of catfish provides secretion of mucous, which may participate in mechanisms of immune functions. Hence, this finding is crucial in understanding the functional influence of these differences in the integument, providing a perception of the adaptation of several types of local fishes to their aquatic environments.