colors

Dear Jess:

Congratulations on doing so well with your Mustangs (Hippocampus erectus)!

Yes, in general, you are correct about the coloration. Tropical seahorses typically darken in response to stress, and brighten or lighten in coloration during their various social interactions. So the basic coloration a seahorse assumes can be a reflection of its emotional state: when excited, seahorses typically brighten in coloration, reflecting a state of high arousal. On the other hand, fear, anxiety and distress are generally accompanied by dark, somber hues.

Seahorses will typically brighten during social interactions, such as their courtship displays, morning greeting rituals, and mating attempts. Likewise, when competing for mates, seahorses may go through characteristic color changes during their confrontations and competitions. If I had to guess what was going on with your smallest Mustang that has turned white and become more active, I would say that the seahorse was in courting mode and showing a healthy interest in courtship and breeding. In the wild, the breeding season for our native American H. erectus begins in April and lasts until the seahorses move into deep water with the onset of winter, so mating overtures are especially common this time of year, which is the heart of the breeding season.

So my best guess is that your small seahorse that has adopted the completely white coloration, except for a darker face, is perfectly healthy and hoping to interest the larger Mustang in mating. In other words, I suspect that the change in the seahorse’s coloration is more of a response to her hormones and biological clock rather than to the colorful new hitching posts that you have added.

Tropical seahorses typically lighten or brighten coloration when they are courting. For example, dark colored Hippocampus erectus typically turn a silvery white or pale cream color when courting, and may also assume pastel yellow coloration when displaying. They will retain this light coloration for several days throughout the courtship process during initial pair formation, as well as for a short period (10-30 minutes) during their daily greeting ritual thereafter.

This change in coloration is known as "Brightening," and typically involves the seahorse turning much paler or later in coloration, with the exception of the head or face and dorsal surface of the seahorse, which usually remain quite dark. This has the effect of making the seahorse more conspicuous and signals its interest in mating.

However, low oxygen levels (or high CO2 levels) can also cause seahorses to fade and they will blanch when subjected to hypoxic conditions. So a seahorse that assumes an unusual pallor may not be getting enough oxygen. In that case, however, the pale coloration will be accompanied by respiratory distress — huffing, rapid respirations, or labored breathing.

Since your pale pony is not showing any signs of respiratory distress, I believe the seahorse is perfectly healthy, Jess, but you might want to check the dissolved oxygen levels in the aquarium to make sure.

Adding a colorful hitching posts was a good thought, Jess, and it may pay off for you down the road if one of the seahorses adopts one of the colorful pieces as its home base or favorite perch. You can never tell what might catch a seahorses eye and trigger a corresponding change in coloration, as discussed below:

Mildred Bellomy provides a perfect example of how this works in the Encyclopedia of Seahorses:

<Open quote>
Elizabeth Goetz of Miami, Florida has kept one or more seahorse stables in her home for many years. She wrote the following anecdote about one of her seahorses that "turned red with envy."

"About five or six years ago, it was just about this time of year, [Christmas], we began our holiday decorating. Our own is not the simplest place to decorate for special occasions in that we have so many aquariums — approximately 35 at the time. Fourteen of these tanks were the homes of seahorses (Hippocampus hudsonius). [Editor’s note: Hippocampus hudsonius is an outdated synonym for Hippocampus erectus.]

"After completing the superficial home decorating, we decided it would be a grand idea to really go all-out with the holiday scheme and include the aquariums. On checking through our collection of assorted Christmas bric-a-brac, we found a number of ceramic items suitable for display in sea water. There were Christmas trees in north-woods green, gaily ornamental angels lovely enough to have stepped from the very gates of Heaven, winged carolers, haloed mermaids, etc., and lo and behold! — one, red-robed, sitting Santa Claus, with the most adorable facial expression one could imagine. Here, then, was ample material to decorate to one’s heart’s content.

"The walls of the dining room are lined with 10- and 15-gallon aquariums so we chose the most prominent 15-gallon tank for this pixie-like Santa. This was the home of five seahorses and they, too, seemed really happy with the decorating idea. We will not argue the point that any other smooth ceramic piece would have pleased them equally, but it is more satisfying to believe that the seahorses joined in with the holiday spirit. Nevertheless, almost as soon as their former hitching posts were removed and a Christmas item put in its place, the seahorses wrapped their respective tails around the new items and were completely at home again. Though scientists may adamantly disagree, we firmly believe fish do have varied personalities, even within their own species. Ask any hobbyist. We have had friendly seahorses, unfriendly ones, and downright cussed critters; the timid, placid, bold, and boisterous, and all of these and more personality traits were observed in H. hudsonius alone.

"All of the foregoing is merely to set the stage for our tale of the seahorse that turned red with envy.

"Our little seahorse star of this story was the most calm and timid of the five in our Santa aquarium. He would cruise calmly from his hitching post for exercise and return to his own station a short distance from the Santa, never trying to usurp the throne of another of his tankmates. The others did claim Santa as a resting place. Seldom was the time when Santa didn’t have the tail of a seahorse wrapped gently around an arm that rested on his pack, or around the tipped-up tassel of his toboggan. Our calm but "envious one" would stare in Santa’s direction almost constantly, while resting. It might be well, at this point, to emphasize that Santa was the only red-colored object or part of this aquarium. This previously dark (brownish) seahorse — originally colored the same as the other four — turned bright red. His change occurred gradually, over a period of about a week and it is quite true, he became a most beautiful red for the holidays."

Now we are well aware of color changes in nature, assumedly for protective measures, and being mindful of the fact that this timid little fellow did not cling to red-robed Santa, but remained some distance away, what then could the whimsical-minded, season-inspired person presume other than that the most peace-loving seahorse in the aquarium bathed himself in the reflected glory of the mythical man-of-the-hour, the one and only Santa Claus. <Close quote>

Notice that the seahorse reverted to its usual dark brown coloration when the scarlet-clad Claus figurine was removed from the aquarium after the holidays.

The moral of this story is that you can never tell what might catch your seahorse’s eye and trigger a corresponding color change in response to a change in its immediate environment. With that in mind, some hobbyists have experimented with brightly colored aquarium backgrounds and achieved surprising results. For instance, I have received reports that a bright orange aquarium backing can stimulate vivid color changes in some seahorses, although the result is often not what you would expect. (One wonders if Hippocampus perceives all colors the same way we do.) Don’t hesitate to experiment until you find the right combination that works well for both you and your seahorses.

Transitory color changes can be achieved rapidly, in a matter of moments, but long lasting transformations occur gradually, and may take days to complete. This is often the case when a seahorse adopts a favorite hitching post and makes it his home base or center of operations. When that happens, the seahorse will often assume a color that closely matches its chosen resting spot so it blends in with its background when hanging out at headquarters. This is akin to the situation with the ceramic Santa; the color matching occurs slowly and, once the transformation is complete, the seahorse intends to keep its new coloration indefinitely.

Best of luck with your Mustangs, Jess!

Respectfully,
Pete Giwojna