Is my seahorse sick?

Dear James:

Yes, sir, that’s correct – if the 25% water change you performed using the saltwater from your LFS was responsible for the big jump in the specific gravity of the aquarium and the significant drop in the pH, then there is no doubt that the water you obtained from the store must have been very high in salinity and very low in pH, indeed.

So I can understand the argument that if the saltwater was that much out of whack, somebody would have noticed and other customers who purchased saltwater from the LFS would also have had problems as a result, James. That makes sense.

And it’s perfectly plausible that the rise in the specific gravity from 1.0245 to 1.026-1.027 could have occurred gradually over a period of weeks due to evaporation without causing any particular problems for the aquarium inhabitants. Likewise, a gradual drop in the pH over a period of days or weeks would also not have been problematic, and could have gone unnoticed if you were not checking your aquarium parameters regularly, James. So it’s certainly possible that the water you obtained from your LFS was not responsible for the jump in salinity or the drop in pH. And if the change in the salinity and the change in the pH took place gradually, over an extended period of time, they would not have had harmful effects on the aquarium inhabitants.

But it is equally clear that the water change you performed had a catastrophic effect on the seahorses, since immediately afterward, one of them swooped up to the top of the tank in obvious distress, sank back down to the bottom, and was dead shortly thereafter. And all of the other seahorses were also obviously stressed out to varying degrees immediately following the water change.

So it seems that something went horribly wrong with the water change nevertheless, James, and if it was not that the replacement water you used was much higher in salinity and much lower in pH than the aquarium water, then something else was amiss with the replacement water instead.

It is possible that the replacement water was contaminated in some way, sir, as we will discuss in more detail below, but I cannot think of any such tax and or contaminant that would be specific to seahorses and not affect the other aquarium inhabitants as well, especially the delicate invertebrates.

So let’s begin by examining some of the other environmental problems and contaminants or toxins that can have a detrimental effect on the aquarium and its inhabitants.

Environmental Diseases Associated with Water Quality

Ammonia poisoning and nitrite toxicity are the most common of these problems (Indiviglio, 2002). Ammonia is highly toxic to fish and invertebrates in even small amounts (> 0.01 mg/L or ppm). Nitrite is slightly less poisonous to fishes, but deadly to some invertebrates at very small concentrations (0.01 mg/L or ppm). To be safe, ammonia and nitrite levels must be kept at zero at all times.

Dangerous levels of ammonia and nitrite can build up in the aquarium for many reasons. Failure to cycle the tank properly and establish the biofilter is a common beginner’s mistake, as is adding too many specimens too soon before the biofilter can adjust to the heavier bioload (i.e., new tank syndrome). Impairment of the biofiltration can also cause ammonia and nitrites to reach dangerous levels. This can result from medicating the main tank, a lack of oxygen for the beneficial aerobic bacteria due to a pump failure or power outage, disrupting the live sand bed too deeply when cleaning the substrate, and so on. The undetected death of tankmate such as a starfish or large snail can lead to harmful ammonia and/or nitrite spikes after it begins to decompose, as can overcrowding and overfeeding. Transitory ammonia spikes are a common problem following a heavy feeding.

Seahorses suffering from ammonia and/or nitrite poisoning will struggle to breathe. The symptoms to look are a loss of equilibrium, hyperexcitability, increased respiration and oxygen uptake, and increased heart rate. At extreme ammonia or nitrite levels, fish may experience convulsions, coma, and death. Seahorses exposed to less extreme ammonia levels will struggle to breathe. They will be lethargic and exhibit rapid respiration. They may appear disoriented, periodically detaching from their hitching posts only to sink to the bottom. They will be lethargic and exhibit rapid respiration. Test kits can often confirm your diagnosis by revealing unacceptable levels of ammonia and/or nitrite in the water, but transitory ammonia splikes (following a heavy feeding, for example) may not be detected by testing the water after the fact.

The appropriate treatment is to immediately transfer the seahorses to clean saltwater in a hospital tank and add methylene blue, which aids oxygen transport in the blood. Methylene blue will help seahorses with ammonia poisoning to breathe, and can actually reverse the effects of nitrite toxicity. While the seahorses are undergoing treatment, partial water changes will reduce the levels of ammonia/nitrite in the main tank. The cause of the problem must then be determined or corrected. This can be as quick and easy as finding and removing a dead specimen or as difficult and time consuming as recycling the entire tank.

Heavy metal poisoning is another environmental disease hobbyists must sometimes contend with. Even tiny concentrations of heavy metals are deadly to marine fish and invertebrates. This used to be a common cause for concern among marine aquarists when steel-framed aquariums were commonplace, but the advent of all-glass tanks and acrylic aquaria have greatly reduced such problems.

The chief offender nowadays is copper, which usually becomes a problem when the hobbyist overdoses the tank with a copper-based medication (Indiviglio, 2002). Other times copper enters the aquarium in tap water used for water changes or topping off the tank. The copper is leached into the tap water from copper pipes and plumbing (Indiviglio, 2002).

Other heavy metals (iron, lead, and aluminum) sometimes also present a problem when they are accidentally introduced to the aquarium in rocks, gravel, ornaments or decorations. Some of rocks and gravel sold (e.g., red flint) for freshwater use are unsafe in marine tanks because of a high metal content. The same is true for many aquarium ornaments and decorations (Giwojna, 1990). Be especially wary when purchasing artificial plastic plants for the aquarium. Stick with calcareous rocks and gravel and make certain any ornaments or plastic plants you consider are designed for use in marine aquariums and certified to be safe.

Even the popular sponge or foam filters are often a hazard. Many of them contain metal weights as ballast to hold them on the bottom, which is fine in freshwater but can be deadly in a saltwater setup when the metal slugs corrode and leach heavy metal ions into the water.

Seahorses suffering from heavy metal poisoning will act as if they are falling-down drunk. They will be listless and loggy, and if they attempt to move, they will be disoriented, bump blindly into things, and have great difficulty maintaining their normal equilibrium and balance (Giwojna, 1990). And they will be breathing hard and fast.

Treatment is as for ammonia/nitrite poisoning — get them into clean saltwater ASAP, identify the source of contamination and eliminate it, and change out the water in the main tank. Polyfilter pads pull out copper and many heavy metals and may be especially useful in such a situation.

Contamination of the aquarium water with household chemicals is another common problem for the hobbyist (Indiviglio, 2002). Avoid using anything that gives off strong fumes anywhere near your aquarium! This includes bleach, paint, lacquer, varnish, paint thinner, turpentine, insect sprays, bug bombs, pesticides, hairy spray, cigarette smoke, and household cleaners of all kinds (Giwojna, 1990).

Even if the aquarium is tightly covered or sealed with plastic, airborne contaminants from fumes and aerosols will still be pumped into the aquarium from the air pumps (Indiviglio, 2002). To prevent this from happening when you must use such products near an aquarium that cannot be moved, disconnect the air pumps first and work only in well-ventilated area. Use submersible powerheads to maintain circulation in the covered aquarium, work fast, and air out the room thoroughly before you reconnect the air supply.

Medicating the aquarium is the worst possible thing you can do when seahorses are suffering from diseases related to water quality or environmental problems such as the toxic conditions described above (Giwojna, 1990). Afflictions such as these are not caused by parasites or pathogens, so medicating the tank not only fails to address the problem, it actually makes matters worse (Giwojna, 1990). Chemotherapeutic agents can be harsh on the seahorses, especially when they are already weakened due to poor water quality or actual poisoning. Worse yet, they are often hard on the biofilter as well and apt to further degrade water quality by killing off beneficial Nitrobacter and Nitrosomonas bacteria.

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.

Hypoxia due to low oxygen levels or high carbonic dioxide levels is another environmental condition that has been known to kill seahorses suddenly and without warning. This often tends to happen overnight when CO2 naturally rise as O2 levels are dropping due to the reversal of photosynthesis.

As you know, while they are photosynthesizing during the day, zoanthellae and algae consume CO2 and produce O2, but at night, in the absence of light, this process is reversed and the photosynthetic organisms consume O2 and give off CO2 instead. Seahorse setups in general are susceptible to such problems because hobbyists are so conscious of their seahorses’ limited swimming ability that they tend to leave their aquariums undercirculated. Poor circulation and inadequate surface agitation can lead to inefficient oxygenation and insufficient offgassing of carbon dioxide.

Seahorses are more vulnerable to low O2/high CO2 levels than most fishes because of their primitive gills. Unlike most teleost (bony) fishes, which have their gills arranged in sheaves like the pages of a book, seahorses have rudimentary gill arches with small powder-puff type gill filaments. Seahorses are said to have “tufted” gills because they appear to be hemispherical clumps of tissue on stems. Their unique, lobed gill filaments (lophobranchs) are arranged in grape-like clusters and have fewer lamellae than other teleost fishes. Because of the difference in the structure and efficiency of their gills, seahorse are unsually vulnernable to hypoxia when CO2 levels are high and/or O2 levels are low.

Most deaths due to hypoxia occur when the water pump or filter fails during the night, or there is a power outage overnight when the aquarist is unaware, cutting off the filtration, water circulation, and aeration of the aquarium with devastating results.

Sometimes the invertebrates we had to of the aquarium for decorative purposes or to bolster the cleanup crew can cause problems by releasing toxins into the water under certain circumstances.

For example, Zooanthids and polyps can release harmful chemicals when they are waging border battles with other corals in close proximity, as discussed below:

“Zooanthus and Palythoa both contain very toxic chemicals, that can be dangerous to both reef inhabitants and humans. The most well known is Palytoxin, which has been documented as one of the most poisonous marine toxins known (Mereish et al, 1991). Palytoxin can affect the heart, muscles, and nerves leaving its victim in paralysis, and possibly death. Because of the toxin, you should never handle Zoanthus or Palythoa with open wounds, nor should you touch your mouth or eyes after handling the species. (We recommend the use of disposable latex gloves) When propagating either of the species, it is critical to remember that the slightest rub of an itchy eye, or even a small cut from a hang nail, might be enough to land you in the hospital. In the aquarium, some rapid growing Zoanthus colonies can be aggressive to stony and soft corals, but in general, they are very peaceful, and you can slow the growth rate by the controlling the overall nutrient load of your tank.”

Likewise, sea cucumbers can sometimes present the problem in that regard as well. Some sea cucumbers release toxins (holothurin and holotoxin) while alive when threatened (or even after death, in some cases). These toxins can be quite deadly to fishes but don’t seem to affect most invertebrates. Such rare Holothurian-related aquarium accidents have become known as “cuke nukes,” and if your seahorse tank was using sea cucumbers as sand sifters to maintain the sand bed, that’s a possibility you should also consider, James.

Okay, sir, those are some of the water quality problems, contaminants, and toxins that can have an adverse effect on the aquarium inhabitants. Let us know if the replacement water you brought home from the LFS or the aquarium itself could have been exposed to are contaminated by any such substances around the time that this problem occurred.

Best of luck figuring out what went wrong and correcting the problem, James.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support