Temperature

Dear Tamy:

When it comes to the water temperature in a small, closed-system home aquarium, my experience has been that Mustangs and Sunbursts are more comfortable closer to 75°F rather than closer to 80°F, Tamy.

At the Ocean Rider aquaculture facility in Hawaii, Mustangs and Sunburst are raised at a constant temperature of 75°F, and they are most comfortable with stable water temperatures in the range from 72°F-77°F. They can begin to experience heat stress and associated health problems in a home aquarium when the water temperature approaches 80°F or above for any length of time.

Also, I should point out that when you are adjusting the water temperature of the aquarium water while seahorses are living in your aquarium, you must be careful to do so very gradually, which means taking care not to raise or lower the water temperature more than 2°F per day.

When raising the temperature upwards, it is always a good idea to increase the surface agitation and aeration in the aquarium as you do so, in order to facilitate better gas exchange at the air/water interface and to promote more efficient oxygenation, because the warmer the water is, the less dissolved oxygen it can hold, and seahorses do best when the dissolved oxygen levels are near the maximum.

In your case, Tamy, if you find that your seahorses were more active and gregarious at a slightly lower water temperature, then I would gradually drop your water temperature a degree or two until you are back to the comfort zone for your particular ponies.

Best wishes with all your fishes, Tamy!

Respectfully,
Pete Giwojna, Ocean Rider Tech Support

Dear Tamy:

Oh, sure – Ocean Rider Mustangs and Sunbursts will happily breed at a water temperature of 75°F, Tamy. As I mentioned, the tropical seahorses at the Ocean Rider aquaculture facility are raised in natural seawater at a constant temperature of 75°F, and they breed like bunnies at the seahorse farm! Of course, this includes the ever popular Mustangs and Sunbursts, Ocean Rider’s strains of captive-bred-and-raised Hippocampus erectus seahorses.

In my experience, the photoperiod of the aquarium – the length of time the aquarium is lighted each day – has a much more profound effect on the breeding behavior of tropical seahorses in captivity than water temperatures within the range of 72°F-78°F or so. In a nutshell, seahorses breed best when provided with a photoperiod of at least 12 hours a day, and providing your ponies with significantly less light each day can inhibit breeding.

To understand why the photoperiod is so important for regulating breeding, we must first understand how the light-dark cycle regulates the levels of key hormones that control breeding. Gonadotropin (GtH) is a hormone that stimulates the growth and activity of the gonads and thus controls reproductive activity in vertebrates. It is secreted by the pituitary gland and stimulates the growth and function of the ovaries and testes. The levels of gonadotropin in the body are in turn regulated by melatonin, a hormone secreted by the light-sensitive pineal gland in response to darkness. Among a great many other functions, melatonin switches on a recently discovered enzyme known as gonadotropin inhibitory hormone, thus reducing the levels of gonadotropin in the body and shutting down reproduction (Sanders, 2005).

In other words, when the days are shortest and there is less sunlight, melatonin secretion is high and the levels of gonadotropin are reduced accordingly, causing the gonads to shrink and turning off reproduction. Likewise, when the days are longest and there is more sunlight, melatonin secretion is low and the levels of gonadotropin are high, stimulating the gonads and triggering reproductive activity (Sanders, 2005). So that’s something to keep in mind when you are hoping to curb the romantic tendencies of your Hippocampus erectus, Tamy – you need to make sure that the main tank is darkened enough to trigger the secretion of melatonin by the pineal gland in response to the hours of darkness. Keeping the aquarium illuminated for no more than 8-10 hours will usually do the trick.

On the other hand, if you want to encourage your seahorses to breed in a home aquarium, maintain stable water temperatures of 75°F-77°F and keep the aquarium light on for at least 12 hours a day for best results. If you maintain good water quality and provide your seahorses with a nutritious diet, and provide them with a suitable photoperiod, sooner are later, nature will do the rest and your Mustangs and Sunbursts will breed readily in the aquarium.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support

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.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support