Pete Giwojna

Dear Tamy:

Yup, algae often grows on the exoskeleton of seahorses, typically on their head and neck which are closest to the light source, particularly when they are kept in reef tanks with high-intensity lighting. In most cases, Tamy, that’s perfectly normal and nothing at all to be concerned about. Seahorses often encourage algae to grow on them as a protective device to enhance their camouflage, and it’s often best simply to ignore any such growth.

We are all well aware that seahorses can change color to blend into their backgrounds, and that Hippocampus is capable of growing or shedding dermal cirri, which are long filaments and branching extensions of its skin, as called for in order to match its immediate environment. To complete its disguise, the seahorse allows algae, bryozoans, hydroids, and other encrusting organisms to grow on its body, thereby rendering it all but invisible in its natural habitat. In fact, its skin contains polysaccharides which are believed to encourage algal growth, thereby helping it disappear into its surroundings. This vanishing act is so convincing that, even when they are collected by hand seining, seahorses often go undetected amidst the plant matter that accumulates in the net. Unless the collector is really diligent, he will lose a large proportion of his catch simply because many specimens will be overlooked and thrown back with the debris. In short, Tamy, it’s perfectly normal for algae to grow on seahorses.

In most cases, it is best simply to ignore any such algae growth. However, when the algae growth becomes excessive, it can sometimes become a source of irritation for the seahorses. If you find the algae growth to be unsightly or excessive, or your ponies find it irritating, you can certainly brush it off very gently using a soft camel’s hair artist’s paint brush, Tamy. Just be very careful when you are handling the seahorse and gently swishing away the algae so that you don’t remove any of the seahorse’s protective slime coat if you can possibly avoid it.

The seahorse’s pliant skin or integument is of course 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, 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. When handling a seahorse, it’s important to wet your hands first in order to avoid removing too much of the protective slime coat.

So feel free to very gently brush away the algae as long as you take the necessary precautions and don’t disturb your seahorses’ protective slime coat any more than necessary, but you should be aware that the algae is likely to regrow if you don’t also address the conditions in your aquarium that are promoting the algae growth. This may mean adjusting your photoperiod or changing the type of lighting you are using, or eliminating any phosphates or nitrates that may be encouraging the growth of nuisance algae.

In short, Tamy, if you find the algae growth to be unsightly or your seahorses find it to be irritating, it can be very gingerly brushed off using a soft camel’s hair artist’s paint brush. Go to a craft store and select a few of the camel’s hair paintbrushes of appropriate size. 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.

Okay, Tamy, that’s the lowdown on carefully brushing excess algae growth away from your seahorses. If it is done very carefully and gently, it will do the seahorses no harm other than the temporary stress of being handled while you are manually removing the algae.

However, simply brushing away the excess algae growth is often not the best option. Handling seahorses to remove the algae is always somewhat stressful for them, and as long as the conditions in the aquarium are the same – with the lighting unchanged and elevated levels of nitrates and/or phosphates still present to fuel the growth of nuisance algae – the unwanted algae is apt to grow right back again before you know it.

I understand that you have recently increased your photoperiod to 12 hours in order to encourage your seahorses to breed, Tamy, so you would prefer not to shorten the period of time that your aquarium is illuminated in order to address the algae problem. In that case, considered downgrading the intensity of the lighting, rather than reducing the hours that the aquarium lights are turned on. If you do not have live corals that require high intensity lighting, just switch to an ordinary low-wattage fluorescent light source instead. A low powered fluorescent tube will still provide plenty of lighting to stimulate the pineal gland in your ponies and stimulate breeding, but will be less likely to encourage the growth of unwanted algae.

At the same time, make sure you keep the nitrate levels and phosphate levels in your aquarium as low as possible to discourage the growth of film algae, Tamy, and you should be able to control the algae growth. Let me know if you need any suggestions regarding the best way to eliminate excess nitrates are phosphates from your aquarium and I’d be happy to provide you with some specific recommendations in that regard.

Best wishes with all your fishes, Tamy.

Pete Giwojna, Ocean Rider Tech Support

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