Re:how to get color back?

Pete Giwojna

Dear Pat:

Seahorses are truly the chameleons of the sea with a propensity for changing color in response to a wide range of environmental factors, hormonal influences, and behavioral interactions.

Although Ocean Rider (OR) seahorses have been endowed with a palette of pigments rich in bright hues, they are not like albinos or lutino or melanistic mutants that are "locked" into their white or yellow or black coloration respectively. Such mutants are a certain color because they are genetically unable to manufacture other pigments; ORs are not. Rather, ORs are genetically equipped to express a wide range of vivid colors, and each type has a built-in predisposition towards a wardrobe of certain shades. But they can and will change colors to reflect their mood, environment, and well-being, as well as to interact with other seahorses.

Seahorses accomplish color changes through the contraction or expansion of pigment cells known as chromatophores. Each chromatophore is a contractile cell or vesicle containing liquid pigment and capable of changing its form or size, thus causing changes of color in the skin of the animals that possess them. The chromatophores may be under nervous control and able to change very rapidly or under hormonal control and able to change only relatively slowly.

In seahorses, the chromatophores are branched (dendritic) cells, within which the color pigment can be moved. When a chromatophore contracts, all of its pigment is concentrated in one small spot in the center of the cell, resulting in the loss of color in the fish. When a chromatophore expands, the pigment spreads throughout the entire cell to all its branches, resulting in bright color.

Different types of chromatophores contain different pigments such as melanin (black), xanthin (yellow), lipochrome (orange), erythrin (red) and so on. The different types of chromatophores are named according to the type of pigment they contain (e.g., melanophores, erythrophores and xanthophores). These specialized pigment cells are usually stacked upon each other or clustered in groups. Hippocampus is typically endowed with 3 or 4 different types of chromatophores, and all other colors are derived from these 3 or 4 basic pigments. The exact color the seahorse displays at any given time therefore depends on the concentration of these pigment cells, how close the cells are to the surface of the skin, and which chromatophores are expanded or contracted at the moment.

For example, seahorses have no blue pigment cells, but the color blue can be approximated nonetheless. A low concentration of melanin (black pigment) deep in the dermal layer gives the skin of the fish a bluish cast. Achieving a blue tint in this way while simultaneously expanding xanthophores (yellow pigment cells) produces shades of green, and maintaining a bluish background color while opening erythrophores (red pigment cells) yields shades of purple and violet. Likewise, a seahorse that has no orange pigment cells can still assume a bright orange coloration by simultaneously expanding its xanthophores (yellow pigment cells) and erythrophores (red pigment cells) to the fullest. The exact shade of orange it becomes and its brightness is determined by the proportion of yellow to red cells it opens, how fully they are expanded, and how close to the skin’s surface they are. Obviously, a seahorse that is black has all its melanophores expanded and a seahorse that is white has ALL of its chromatophores contracted so that all the wavelengths of visible light are reflected back to the observer, and so on.

In seahorses, melanophores are the most common of these pigment cell types. They contain the pigment melanin, which gives most seahorses their typical black or dark brown coloration. Essentially melanin absorbs the entire visible light spectrum and looks black because no light is reflected back to the observer. When a melanophore is open and fully expanded, the melanin it contains is dispersed throughout the cell, and when all the melanophores are opened at once, melanin is distributed evenly across the surface of skin, rendering the seahorse black. Seahorses typically respond to stress by expanding their melanophores and darkening this way.

The different types of pigment cells seahorses possess varies from species to species. Hence, not all seahorses have the same palette of colors at their disposal. Some seahorses can never turn red because they lack erythrophores; red is simply not in their wardrobe. In general, tropical seahorses tend to have brighter colors in their repertoire than temperate species. And deep-water seahorses often have more red and orange pigment cells than other seahorses. In order words, different seahorse species have different coloration due to the differential proliferation of chromatophore cell types.

Colorful Ocean Riders, for example, are not homozygous recessives nor or they mutations that are unable to manufacture certain pigments altogether. But they do exhibit differential proliferation of chromatophores and this gives each type a predisposition to display certain colors. Mustangs have a preponderance of melanophores, for instance, and tend to be dark (earth tones) or cryptically colored most of the time. But ‘stangs also have bright pigment cells and they can brighten up when the occasion calls for it, such as during courtship or when competing for mates.

I own a pair of these spirited steeds myself, and have watched them go through a number of color phases from month to month. One has settled on gray-green as its base coloration for the moment, and the other ranges between rust, burnt umber, and orange, but always with contrasting beige bands. Last season, the male adopted a rich ochre yellow as his everyday attire (still with the same beige bands, though), while the female displayed a dark purplish ensemble with definite greenish highlights. When courting, they consistently brighten to a pearly white and a creamy yellow respectively. They make a handsome couple, and I find my Mustangs to be very attractive specimens in all their guises.

As for their coloration, Sunbursts are equipped with a full range of chromatophores (pigment cells) and can display a wide range of colors, but they are predisposed towards the sunset colors (yellow, gold, peach and orange) when conditions are to their liking. They have proportionally fewer melanophores (black pigment cells) than Mustangs, which are typically dark brown or black, so the background or base coloration of the Sunbursts tends to be lighter. Yellow and orange specimens predominate, but they also display whitish, tan, pearly and even brown color phases at times. You can expect your Sunbursts to go through a number of color phases and color changes over the months.

Sunbursts have fully functional melanophores, albeit somewhat fewer of them, in addition to their bright pigment cells and they will darken in response to stress or change their coloration to reflect changing circumstances and conditions. As John suggested, you might try adding a couple of brightly colored yellow or orange or red hitching posts to your tank if you want to encourage them to retain their sunset colors most of the time (more on that later).

The hobbyist should also be aware that there are any number of environmental conditions that can affect the coloration of seahorses, often by affecting the ability of chromatophores to contract and expand. These include the following factors:

Stress — seahorses often respond to stress by darkening.

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.

Social interactions — seahorses often brighten during their courtship displays; pair-bonded seahorses likewise brighten during their morning greeting rituals, and rivals go through characteristic color changes (see below) during their confrontations and competitions.

Competition for mates — dominant individuals brighten; subordinate seahorses darken in submission.

Poor water quality — high levels of nitrogenous wastes (e.g., ammonia, nitrite or nitrate) can cause chromatophores to contract and colors to fade.

O2/CO2 — low oxygen levels (or high CO2 levels) can cause colorful seahorses to fade and they will blanch when subjected to hypoxic conditions.

Background colors — seahorses will often change color in order to blend in with their immediate surroundings.

Medications — some antibiotics and malachite-green-based remedies negatively affect color.

Tankmates — seahorses may change their base coloration to blend in with the rest of the herd or to match their mate (or a potential partner). This can work both ways: a dark seahorse may brighten up and assume vivid hues when introduced to an aquarium with bright yellow or orange tankmates, just as a brightly colored seahorse may darken and adopt subdued coloration when placed amidst drab tankmates. Of course, seahorses are not respondsing to peer pressure when they conform in this manner; rather, this is probably instinctive behavior. In nature, it’s not healthy to be too conspicuous and stick out in a crowd since an individual that stands out from the rest of the herd draws the attention of potential predators to itself.

Temperature — chromatophores tend to contract at high temperatures (above the seahorse’s comfort zone), causing colors to fade; cooler temps within their optimal range can make pigment cells expand, keeping colors bright.

Disease — skin infections (bacterial, fungal, or parasitic) can cause localized loss of pigmentation or discoloration of the affected areas.

Diet — seahorses cannot synthesize the pigments used in their chromatophores. It is therefore important to enrich their food with pigments such as carotenoids in a form that’s easy for them to absorb. If color additives are not provided, the chromatophores will gradually lose their pigments and the seahorse’s color can fade. Vibrance, for example, is exceptionally rich in Vitamins A and C as well as natural carotenoids, which are not found in Mysis relicta. This is important because the carotenoids are a class of yellow to red pigments, which include the carotenes and the xanthophylls. Like all cells, individual pigment cells have a limited life expectancy in the body and must be regularly renewed. Marine organisms cannot synthesize carotenoids, so if they do receive adequate amounts in their diet, they will have difficulty replenishing their red and yellow pigments. This means that the colors of bright yellow, orange, and red seahorses will gradually fade over time if their daily diet is lacking in carotenoids. So don’t neglect the enrichment step in your daily feeding regimen! If seahorses are fed a strict diet of Mysis relicta without additional enrichment, they may begin to develop dietary deficiencies over time, and both their health and coloration will eventually suffer.

Lighting — seahorses may darken in response to UV radiation as a protective measure, whereas bulbs that emit wavelengths of light shifted towards the red end of the visual spectrum (i.e., Grolux fluorescent tubes) can greatly enhance the coloration of red, orange or purplish seahorses to the point that they almost literally glow.

In short, Pat, the change in your Sunbursts’ coloration is not unusual and should not be a cause for concern. Your aquarium is different from the environment they were accustomed to at Ocean Rider and most likely they have simply changed coloration in response to their new surroundings and different conditions. You can expect them to exhibit a number of different color phases over the coming months and years. Expect them to display brighter colors when they get serious about breeding and courtship.

All of the different factors mentioned above need to be addressed in order to keep your seahorses looking their best and brightest, Pat. I would be happy to discuss some of the measures hobbyists can take to make sure their seahorses look their best, along with a few tips that will often encourage drab seahorses to change color or brighten up.

Like all seahorses, Sunbursts may respond to stress by darkening and expanding their melanophores to signal their distress. When that happens, it doesn’t matter how brilliant their base coloration may be, since the melanin absorbs the entire visible spectrum (black is essentially the absence of color) and none of the underlying colors are able to shine through. Consequently, seahorses may never color-up and look their best if subjected to dubious water quality, unacceptable aquarium parameters, an inadequate diet, or other stressful conditions.

When setting up and maintaining your seahorse tank, your primary goal must therefore be to provide your seahorses with a stress-free environment that meets all of their requirements. Begin by making sure your saltwater tank is properly cycled and by maintaining your water quality within the following parameters: pH 8.2-8.4, specific gravity 1.021-1.025, temperature 72°F-75°F. Strive for stable readings within those limits, and maintain zero ammonia and nitrite at all times.

Elevated nitrates are also stressful to seahorses over the long term, and can keep your seahorses from looking their brightest. For best results, consider using live rock and/or a live sand bed (preferably situated in your sump) in conjunction with a good protein skimmer to help filter your seahorse setup. The skimmer will remove excess organic compounds before they enter the nitrogen cycle, and live rock and a deep sand bed will provide significant denitrification ability, all of which will help keep your nitrates down. Don’t overstock, don’t overfed, remove leftovers promptly (a good clean-up crew is useful here), practice good aquarium maintenance and maintain a sensible schedule for water changes.

Some potential stressors, such as shock and vibration or excess noise and traffic, can be eliminated altogether during the planning stage. The medium of water transmits certain sounds wonderfully well–far better than air, in fact–and like all fishes, seahorses have organs specially designed to detect such vibrations, and are sensitive to external noises and outside sources of shock and vibration. Whether it’s a clunky air pump or compressor, the buzzing ballast from an aquarium reflector, the rattling impeller from a noisy power filter, or something totally unrelated to the aquarium, like a nearby clothes washer/dryer, dishwasher, stereo, television or some such appliance, any source of bad vibes can subject seahorses to chronic low-level stress. Footfalls and nonstop passersby in heavy traffic areas can also be alarming to seahorses, and when they feel threatened they react by darkening or assuming cryptic coloration, resorting to camouflage in order to conceal themselves in the face of potential danger.

To avoid this sort of stress, choose the location for your seahorse tank with care, dampen all potential sources of shock and vibration, and provide a thick pad (cork or Styrofoam is ideal) beneath the tank to deaden vibrations and soften any shocks that might otherwise be absorbed through the base of the aquarium. The aquarium should be situated in a relatively quiet room away from major traffic areas, blasting stereos, blaring TVs and noisy kids. If you have modified your laundry room, utility room, or workshop so it can do double duty as your fish room, you may want to find a less mechanically-cluttered area for your seahorses.

Stray voltage is another common cause of chronic stress for seahorses and other aquarium inhabitants, as well as a much more prevalent problem than most hobbyists suspect. Installing a grounding probe in the tank easily prevents it, and every seahorse setup should be equipped with one. A titanium grounding probe is an inexpensive investment that can safeguard the health of your seahorses. Think of it as an extraordinarily cheap, yet effective life insurance policy that can save your fish-and your hide-in the event of an electrical accident while working on your tank.

As previously discussed, diet also plays an important role in keeping your seahorses healthy and looking their best. Ocean Riders are trained to eat a diet of frozen Mysis relicta enriched with Vibrance. These freshwater Mysids (from Piscine Energetics) are a super food for seahorses, extremely rich in protein and essential fats. In general, the total fat content of freshwater feeder fish and inverts (e.g., FW ghost shrimp and glass shrimp) is shockingly low, but Mysis relicta is a remarkable exception which has several times the fat levels of even highly desirable marine feeder organisms such as saltwater Penaeus shrimp. But as nutritious as it is, Mysis relicta is not a suitable long-term diet for seahorses on its own, and Vibrance has been specially formulated to add certain vitamins, minerals, and additional long chain fatty acids that M. relicta lacks.

For instance, Vibrance contributes high levels of HUFAs (highly unsaturated fatty acids) including the DHA omega 6 and omega 3 series, which are extra long chain fatty acids that are absent in virtually all live and frozen feeds. Most marine organisms, seahorses included, cannot synthesize these long chain fatty acids and must obtain them through their diet. DHA, for instance, has been proven to be essential to high survivability, nerve development, stress management, and proper reproduction in fishes. The combination of Mysis relicta enhanced with Vibrance is a superb, nutritionally complete diet for seahorse that contains everything they need for vibrant good health and long-term survival.

As far as coloration goes, Vibrance is also exceptionally rich in Vitamins A and C as well as natural carotenoids, which are not found in Mysis relicta. This is important because the carotenoids are a class of yellow to red pigments, which include the carotenes and the xanthophylls. Like all cells, individual pigment cells have a limited life expectancy in the body and must be regularly renewed. Marine organisms cannot synthesize carotenoids, so if they do receive adequate amounts in their diet, they will have difficulty replenishing their red and yellow pigments. This means that the colors of bright yellow, orange, and red seahorses will gradually fade over time if their daily diet is lacking in carotenoids. So don’t neglect the enrichment step in your daily feeding regimen! If seahorses are fed a strict diet of Mysis relicta without additional enrichment, they may begin to develop dietary deficiencies over time, and both their health and coloration will eventually suffer.

Once your biofilter is fully established and you are prepared to provide your seahorses with optimal water quality and an ideal, enriched staple diet, you must also take care to furnish your aquarium in a manner that will encourage them to display their brightest colors.

In a drab, largely monochromatic setting, CB seahorses may never look their best. For instance, if you introduce your Sunbursts or Brazileros to an aquarium decorated primarily with the bleached white bones of coral skeletons and a substrate of dolomite, crushed coral or coral sand, you can expect their bright hues to fade quickly. Seahorses rely on crypsis and their ability to blend into their background in order to avoid predators and stay out of trouble, and brightly colored seahorses will feel vulnerable and exposed in such a bleached coral seascape. They will either adopt pale colors or a generalized, drab, nondescript, cryptic color pattern that makes them less conspicuous. The same is true if their tank features algae-covered rock, loads of Caulerpa, and lots of other macroalgaes, and is dominated by browns and greens. Bright red and orange seahorses may not feel at home amidst algal mats or this sort of seagrass habitat, and are apt to revert to earth tones, cryptic patterns, or shades of olive drab.

Therefore, in order to show off your ORs to full effect and encourage them to live up to their potential and retain their true brilliance, it’s a good idea to provide them with a colorful natural setting that will make them feel right at home. This means furnishing their aquarium with appropriate, multi-colored décor. Reef tanks featuring colorful sponges, mushrooms, leathers, and other seahorse-safe soft corals and gorgonians are ideal, guaranteed to keep seahorses feeling right at home and looking their best. If you’re not a reefer, you can often achieve the same effect using "faux" coral, plastic gorgonians and replicas of marine plants to encourage them to retain their natural coloration. Various types of Caulerpa and attractive macroalgaes can then be added to give your tank a welcome touch of green and a bit of living color. Many hobbyists find that a dark substrate, such as black sand, brings out their seahorses’ brightest colors and sets off their vivid hues exceptionally well, as well as being aesthetically pleasing.

Pay special attention to the hitching posts you select. Strive for bright reds, oranges, and yellows in anything your seahorses may adopt as a holdfast. These aquatic equines-especially the stallions-will often choose one particular hitching post as their home base and spend much of there time perched right there (think of your Dad hunkered down in his favorite easy chair in the den). Once they adopt a favorite base of operations like this, they will often proceed to change coloration to match their preferred resting spot. So you want to encourage them to adopt one of the more vivid pieces as a favorite holdfast.

A good way to tip the odds in your favor is to acquire one or more tree sponges for your seahorse tank. Tree sponges are usually brightly colored (red and orange shades are common) and their shape and texture seem to make them irresistible to seahorses as hitching posts. Very often, all the seahorses in the tank can be found clinging to the same tree sponge together, eschewing other nearby holdfasts that appear every bit as comfy and attractive to human eyes. Tree sponges are everything both you and your seahorses are looking for in terms of aquarium décor.

Right now, it sounds like the predominant colors in your aquarium are still brown (rockwork and hitching posts), white (rocks and coral), and olive drab (microalgae growth) and that could be part of your problem.

But it sounds like you’re on the right track, Pat. Maintaining optimum water quality, feeding your seahorses plenty of Vibrance-enriched Mysis, and adding more colorful hitching posts should all be helpful. Keep your pH stable, maintain water temperature in their comfort zone, and keep the dissolved oxygen levels high and the nitrate levels low. Eliminate all of the common aquarium stressors and your seahorses will take it from there.

That will also help assure that your seahorses will display a healthy interest in courtship and breeding. Provide them with pristine water quality, a nutritious diet, and a stress-free environment, and then sit back and let nature take its course. Just be patient. The breeding imperative is very strong in Hippocampus, and as your seahorses mature, they will begin to reproduce.

Once they do begin to breed, they will do so relentlessly. Gravid males typically remate within a day or two of delivering their latest brood, and since captive-bred-and-raised seahorses often breed year-round in the aquarium, the result will be mature males that are more or less permanently pregnant. Provide them with good care and conditions to your liking, and sooner or later you’re going to have more broods of healthy young than you can handle.

Best of luck with your new seahorses, Pat!

Happy Trails!
Pete Giwojna

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