Dear Kent and Liam:
Yes, it’s possible that the the red spots you noticed along the dorsal surface of your seahorse could be some sort of algae. I can tell you that algae often grows on the exoskeleton of seahorses, typically on their head and neck which are closest to the light source. That’s perfectly normal and usually nothing at all to be concerned about. Seahorses often encourage algae to grow on them as a protective device to enhance their camouflage, but in most cases I have seen the algae growth was greenish or brownish in coloration.
When algae grows on a seahorse it can be carefully removed as described below, so you might consider brushing off the red spots to verify that it simply algae growth. The best way to do that is to use a soft artist’s brush to carefully swish away the algae.
Go to a craft store and select a few of the camel’s hair or sable paintbrushes of appropriate size. Just be very careful when you are handling the seahorse and gently brushing away the algae so that you don’t remove any of the seahorse’s protective slime coat if you can possibly avoid it. Remember to wet your hands beforehand and observe the following precautions when handling the seahorses:
When handling seahorses, I do not like to use an aquarium net to transfer or manipulate my ponies, since their delicate fins and snouts can become entangled in the netting all too easily. I much prefer to transfer the seahorses by hand. Simply wet your hand and fingers (to avoid removing any of the seahorse’s protective slime coat) and scoop the seahorses in your hand. Allow them to curl their tail around your fingers and carefully cup their bodies in your hand to support them while you clean them with a soft bristle brush.
Composed of solid muscle and endowed with extraordinary skeletal support, the prehensile tail is amazingly strong. Indeed, large specimens have a grip like an anaconda, and when a 12-inch ingens or abdominalis wraps its tail around your hand and tightens its hold, its vise-like grip is powerful enough to leave you counting your fingers afterwards!
In fact, it can be quite difficult to remove an attached seahorse from its holdfast without injuring it in the process. Never attempt to forcibly detach a seahorse from its hitching post! When it feels threatened, it’s instinct is to clamp down and hold on all the tighter. When you must dislodge a seahorse from its resting place for any reason, it’s best to use the tickle technique instead. Gently tickling the underside of the tail where it’s wrapped around the object will usually induce the seahorse to release its grip (Abbott, 2003). They don’t seem to like that at all, and will quickly let go to move away to another spot. Once they are swimming, they are easy to handle.
If you can simply brushed away the red patches along the back of your seahorse, that’s a good indication that it is likely algae growth and nothing to be alarmed about. I don’t know of any disease problem that would manifest itself as red spots confined to the dorsal surface of the seahorse, and it doesn’t sound like any sort of a fungal problem I am familiar with.
If you can get a picture showing the suspicious red spots, that would be helpful in determining whether or not they are problematic.
Best of luck with your seahorses, Kent and Liam! Here’s hoping that your seahorses as simply picked up a little algae growth and that he continues to thrive, none the worse for wear.