No, seahorses do not molt or shed their skin. Seahorses are not like crustaceans that must molt regularly and then re-harden their exoskeletons in order to grow, nor are they like reptiles that shed their skin periodically as they grow. Seahorses are fish with an armor plated exoskeleton covered by a thin layer of skin.
The seahorse’s pliant, scaleless skin or integument is stretched smoothly over its bony exoskeleton, and is its first line of defense against disease. It contains mucus glands, and the slime covering the skin acts as a barrier to ectoparasites and infection. The protective slime can contain antibodies and antibacterial substances (Evans, 1998), and excessive mucus production is often the first sign of an infection or parasite problem. On the other hand, healthy seahorses often have small bright dots on their heads and torsos, which are actually mucus deposits. These beads of mucus glisten like little diamonds and are a sign of vibrant good health (Garrick-Maidment, Aug. 2002). When handling a seahorse, it’s important to wet your hands first in order to avoid removing too much of the slime coat.
Marine fish are always in danger of dehydration because the seawater they live in is far saltier than their blood and internal body fluids (Kollman, 1998). As a result, they are constantly losing water by diffusion through their gills and the surface of their skin, as well as in their urine (Kollman, 1998). The mucus layer acts as a barrier against this, waterproofing the skin and reducing the amount of water that can diffuse through its surface (Kollman, 1998).
It could be that your seahorse is sloughing a little excess mucus, in which case there is nothing to be concerned about.
But if it looks red underneath the piece that is coming off, then it sounds like your seahorse is sloughing some of its skin and exposing the underlying tissue and musculature. That’s not normal at all and is often a symptom of a serious bacterial infection. If that’s the case, the seahorse should be isolated and treated in a hospital tank with broad-spectrum antibiotics and/or topical treatments to the affected area.
It’s very difficult to determine what is going on with your seahorse based only on your brief description that it looks like he is molting, and it would be very helpful if you could send me a digital photograph of the affected seahorse. If you can send me one or more photographs inserted in an e-mail off list ([email protected]), I would have a much better idea of what is happening to your seahorse and how you should proceed if treatment is necessary.
In the meantime, best of luck with your pet shop ponies.