Re:Strange behaviour

Dear Jake:

Of course, it is terribly difficult to try to diagnose health problems from afar when you cannot see the seahorses or the system they are in, and you have no laboratory tests, cultures, skin smears, wet-mounts, necropsy reports or anything concrete to go on to guide your diagnosis, but my first impression is that the seahorse that has been acting strangely may not be ailing at all.

Rather, it sounds more like your Asian Emperor seahorse (Hippocampus kuda) may be displaying a healthy interest in courtship and mating. It sounds like he may be performing courtship displays in an attempt to entice the other seahorse to mate. The change in coloration you noticed, whereupon the seahorse becomes quite pale, is quite characteristic of courting seahorses. When seahorses are courting, they typically change from their normal dark coloration to a much lighter coloration, which makes them relatively conspicuous and is intended to help them attract a mate. This is known as "Brightening," and is typical of all tropical seahorses. (Tell me, Jake — when the seahorse turns pale, as you describe it, does the face or head of the seahorse retain its normal dark coloration? If so, then it’s very likely that he is merely showing off his courtship coloration rather than developing a sickly pallor.)

Likewise, seahorses perform a number of dancelike displays when they are courting. These include shimmying maneuvers known as "Tilting" and "Reciprocal Quivering," and the seahorses adopt a very distinctive posture when they perform these dance moves during which they keep their heads tucked down. Ordinarily, the seahorses will promenade with their bodies held erect and their heads held high but inclined downwards, so as to keep their chins, errr — their snouts tucked tightly against their necks when they perform these courtship displays (Vincent, 1990). It is normal for the seahorse’s respiration rate to increase when they are courting, or anytime they are excited, for that matter, and when the males perform their vigorous pouch displays for the benefit of the nearby female, it often looks like they are having convulsions or seizures.

In short, Jake, the transitory nature of the unusual symptoms or behaviors you are concerned about makes me think that you may be mistaking flirtatious behaviors and the unorthodox courtship rituals Hippocampus performs as indications of distress. At least, I know of no disease process that would cause the sort of symptoms you report, but only sporadically, for five or 10 minutes at a time, after which the seahorse appears to be perfectly normal and healthy again.

Under the circumstances, I think the best thing you can do is to concentrate on maintaining optimum water quality while you observe the seahorses closely to see if the female eventually responds to the male’s overtures, or conversely, to see if you notice any additional symptoms of a disease problem. In the meantime, be very careful to adjust the pH slowly and gradually. Other than the pH running a little low, your other water quality parameters seemed to be fine. Here is some additional information regarding the water chemistry in a saltwater aquarium so you can see which readings are in the normal range and when you need to be concerned if your readings are off:

Basic Water Quality Parameters.

Ammonia (NH3/NH4+):
Natural Seawater Value = 0.010 mg/L
Acceptable Range = 0.000 to 0.050 mg/L
Optimum Level = 0 at all times

Ammonia is highly toxic to both fish and invertebrates in even small amounts (> 0.05 mg/L or ppm). Causes of ammonia toxicity include: immature biofilter (new tank syndrome), impairment of the biological filtration due to antibiotics and other medications, overfeeding, overstocking and dead specimens that go undetected (Webber, 2004). Ammonia levels can also rise after the addition of new animals, after a water change, or following a heavy feeding. Any ammonia level above 0.05 mg/L is a cause for concern, and the source must be found and corrected immediately. Be sure to maintain a good schedule of water changes.

Nitrite (N02):
Natural Seawater Value = 0.010 mg/L
Acceptable Range = 0.000 to 0.100 mg/L
Optimum Level = 0 at all times

Nitrite is slightly less poisonous to fishes than ammonia, but deadly to many invertebrates at very small concentrations. Residual levels of nitrite are common in marine aquariums. Levels of 0.05 or less are of little concern in a fish-only aquarium. If the levels are higher than this, the source should be found and corrected immediately. Even trace amounts of nitrite can wreak havoc among the live corals and delicate invertebrates in a reef tank. High levels of nitrite result from the same causes as ammonia.

Nitrate (N03):
Natural Seawater Value = 0.050 mg/L
Acceptable Range = 0.000 to 20 mg/L
Optimum Level = below 10 mg/L in fish-only tanks; 0 mg/L in reef tanks.

Nitrate is the end product of the process of nitrification, formed during the Nitrogen Cycle by the oxidation of nitrite by aerobic bacteria. Nitrate is relatively nontoxic to fishes, but elevated levels (> 20 mg/L) are stressful to seahorses over the long term and promote the growth of nuisance algae. Reef invertebrates can be much more sensitive to nitrate, and concentrations as low as 0.06 mg/L can cause problems for symbiotic stony corals. Any level above 5.0 mg/L in reef aquariums is a reason for concern and should be corrected immediately. The nitrate level is a good indicator of water quality and rising levels of nitrates are an indication of deteriorating water quality. 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 cleanup crew is useful here), grow and harvest macroalgae, practice good aquarium maintenance and maintain a sensible schedule for water changes.

pH:
Acceptable Range = 8.0 – 8.4 (typically fluctuates between 7.9 at night and 8.4 during the day)
Optimum Level = ~8.2 and stable.

The pH is a measurement of the alkalinity or acidity of aquarium water. A pH of 7 is considered to be "neutral," neither acid or alkaline, while pH levels above 7 are considered to be alkaline or "base," and pH levels below 7 are considered to be acidic. Marine aquaria need to maintain alkaline conditions at all times, and low pH (< 7.6) is especially detrimental to seahorses because it is conducive to Gas Bubble Disease. Normal daily fluctuations in pH are to be expected in the aquarium, and are generally gradual enough not to be stressful (Webber, 2004). Maintaining a sump or refugium with a reverse photoperiod to the main tank can eliminate these natural pH cycles. Regular partial water changes are the key to maintaining stable pH. Buffers can also help but the hobbyist should beware that excessive use of pH buffers may increase KH values to dangerously high levels.

Specific Gravity:
Acceptable Range = 1.020 -1.026
Optimum Level = 1.0245 for most seahorses.

The specific gravity measures the density of a your aquarium water relative to the density of distilled water, and aquarists use it to estimate the salinity of their aquarium water (Trevor-Jones, Dec. 2002). In effect, it’s one way to measure the saltiness of your tank, since the more salt that is dissolved in the water, the denser it becomes. This can also be done by measuring the total amount of dissolved solids in the water, which is expressed as the salinity in parts per thousand (ppt). Hobbyists must remember that constant evaporation of freshwater from the aquarium causes the salts to become more concentrated, which increases the specific gravity or salinity accordingly. Therefore, it is necessary to top off the tank with freshwater regularly in order to make up for evaporation and maintain the desired specific gravity. Seahorses tolerate a wide range of salinity very well and hyposalinity (specific gravity at 1.011-1.015) is often used to help rid them of ectoparasites.

Dissolved Oxygen (02):
Optimum Level = 6 – 7 ppm

High levels of dissolved oxygen are vital to the well being of both fish and invertebrates. The key to maintaining high O2 levels in the aquarium is good circulation combined with surface agitation (Webber, 2004). Wet/dry trickle filters, bio wheels, and protein skimmers facilitate efficient gas exchange and oxygenation. It is important for the hobbyist to monitor the dissolved oxygen levels in the aquarium because a drop in O2 levels is often an early indicator of impending trouble — a precursor of problems ahead. A drop in O2 levels will tip off the alert aquarist and allow corrective measures to be taken, nipping the problem in the bud before it adversely affects his seahorses. Low levels of dissolved oxygen cause lethargy and respiratory distress, and can contribute to a loss of appetite or trigger a hunger strike, in addition to affecting hormone levels and having an adverse impact on a gestating seahorse.

Alkalinity:
Natural Seawater Value = 2.5 meq/L
Acceptable Range = 2.5 to 5.0 meq/L
Optimum Level = 2.5 milliequivalents per litre (meq/L)is best for fish tanks; > 3.0 meq/L is recommend for reef tanks.

The alkalinity is basically a measure of the capability of your aquarium water to resist changes in pH from the addition of acid (Trevor-Jones, Nov. 2002). Acid is continually entering the aquarium, primarily as the result of respiration (CO2) and metabolic wastes produced by the aquarium inhabitants (Trevor-Jones, Nov. 2002). The addition of these acids tends to lower the pH of the aquarium water. The higher the alkalinity of your aquarium water, the more resistant it is to such downward pH shifts (Trevor-Jones, Nov. 2002). The amount of buffers (primarily carbonate and bicarbonate) in saltwater determines the alkalinity, so the alkalinity in effect is the buffering capacity (Trevor-Jones, Nov. 2002). When the buffering capacity of the water is depleted, the pH becomes unstable. A fluctuating alkalinity will lead to serious problems in
maintaining an appropriate pH, as well as problems keeping calcium and magnesium levels within required ranges. Alkalinity test kits can now warn of low buffering levels in time to prevent potential pH problems (Trevor-Jones, Nov. 2002).

Carbonate Hardness (KH):
Natural Seawater Value = 7 dKH
Optimum Level = 7dKH

Carbonate hardness is another measurement of alkalinity. It is usually expressed in the German unit dKH (degrees of carbonate hardness) and is often considered to be the total alkalinity. (Dividing dKH by 2.8 will give you the alkalinity in meq/L.) KH actually a measurement of various carbonates and bicarbonates of calcium and magnesium within the aquarium water (Webber, 2004). Maintaining a stable KH is very desirable since it maintains the buffering capacity (i.e., alkalinity) of the system and prevents subsequent drops in pH. Aside from stabilizing the pH, reef keepers need to maintain KH and high alkalinity in order to assure that the calcifying organisms in the tank flourish. Corals and other calcifying organisms actively use bicarbonate, which is the main component of alkalinity, so the alkalinity of a tank with a lot of calcification can drop quite rapidly.

Calcium (Ca):
Natural Seawater Value = 400 mg/L
Acceptable Range = 350 to 450 mg/L
Optimum Level = 350 – 400 mg/L (up to 500 mg/L in well-stocked reef tanks)

Calcium is a very important element in the water in any marine aquarium and is a vital element in reef tanks. Along with carbonates and bicarbonates, it is required by calcifying organisms such as stony corals, snails and other mollusks, coralline, Halimeda and other calcareous algae, and certain sponges (Trevor-Jones, Apr. 2003). Calcium is a critical parameter for coral growth in reef aquariums, and chronically low levels will cause coral mortality and loss of coralline algae and other invertebrate species. Calcium reserves must therefore be replenished on a regular basis. Regular water changes may achieve this, but reef keepers may require the addition of biologically available calcium to maintain adequate levels (Trevor-Jones, Apr. 2003). Seahorse keepers should be aware that brooding males provide calcium to the developing fry in their pouches, which the embryos probably incorporate into their skeletons. Deficiencies in calcium could thus adversely affect your seahorses’ reproductive success and the health of the fry. In fact, seahorses that receive a diet deficient in calcium often suffer from decalcification of their exoskeleton, a debilitating condition commonly known as “soft plate” disease (Greco, 2004).

Phosphate (PO4):
Natural Seawater Value = 0.030 mg/L
Acceptable Range = 0.000 to 0.250 mg/L
Optimum Level = 0

High phosphate levels are detrimental to marine aquaria. In fish-only tanks, they promote excessive growth of nuisance algae, such as the dreaded hair algae and red slime algae (cyanobacteria), and in reef tanks they also directly inhibit calcification by corals and coralline algae (Holmes-Farley, 2002). Phosphates arrive in the aquarium in fish foods, through tap water, as an ingredient in low-quality carbon and marine salt mixes, and primarily through the waste products of the inhabitants (Webber, 2004). Avoid overfeeding, maintain a sensible schedule of partial water changes, and use only phosphate-free activated carbon for your aquarium. (Carbon is activated two ways, either with steam or with phosphoric acid. The type of carbon that is activated with phosphoric acid contains phosphates, which can be leached back into the aquarium water and promote the growth of nuisance algae. So you will want to avoid that type of of activated carbon. The carton or box that the activated carbon comes in should be clearly labeled and state specifically that it is "steam activated" or "phosphate free" or something to that effect if it’s a suitable brand for your aquarium.) Growing and harvesting macroalgae and protein skimming are excellent ways to reduce phosphate levels The use of a phosphate absorbing resin is recommended to keep phosphate levels below 0.05 mg/L, if necessary.

Redox Potential or Oxidation Reduction Potential (ORP):
Optimum Level = 350 millivolts

The redox potential relates to the degree of water purity in the aquarium, and can be thought of as a measurement of the water’s ability to cleanse itself via oxidation. It is measured in millivolts of conductivity, a unit that provides information about the reduction and oxidation characteristics of the water. (“Redox” is merely a contraction of reduction-oxidation.) Oxidation-Reduction Potentials (ORP) are closely related to the stability of the marine aquarium and can therefore be used as a barometer of water quality. Highly efficient filtration, good aquarium maintenance and management, and the use of ozone in conjunction with a protein skimmer will help to boost redox values.

Seahorse keepers with fish-only systems need not be overly concerned about many of the parameters mentioned above, but I’ve summarized them anyway for the sake of thoroughness and the benefit of reefers who keep seahorses.

Best of luck with your Asian Emperor seahorses (H. kuda), Jake! Here’s hoping they are merely getting serious about courtship and breeding and that you have nothing to worry about, sir.

Respectfully,
Pete Giwojna