Deal With Cuts, Scrapes And Minor Injuries

Tetra’s Dave Hulse looks at how the skin and fins of your fish can become damaged and what to do to help the healing process.

- Dave Hulse

The skin of a fish provides numerous important functions; it is a barrier against the external environment, sealing the internal milieu of the fish and preventing infection by pathogens. Most notably the skin contains the scales, which form a tough outer armour present on most aquarium and pond fishes. The skin is the site of protective mucous secretion amongst other immune factors and houses receptors for touch, smell and even taste. Pigment containing cells called chromatophores are also found in the skin, which are clearly of interest to ornamental fishkeepers.

We can separate the skin of fishes into two principal layers. An inner dermis contains blood vessels, nerves and sensory receptors,scales and connective tissues. Beneath this layer lies the muscle and above lies the epidermis, (‘epi’ meaning ‘on top of’). The epidermal layer contains many layers of cells that are toughened with the protein keratin in many species. Also present are mucous producing goblet cells in the epidermis.

Bony fish scales can be variable in structure, however the majority of species encountered  in aquaria or ponds will have either cycloid or ctenoid scales, the latter being differentiated by the presence of small teeth called ‘cteni’ on the exposed portion of the overlapping scales. Scales arise in the dermal layer and are covered over by the epidermis, and so you can see the loss of a scale is quite a serious insult to the integrity of the fish skin.