Seahorse death

Dear Dymond:

I’m very sorry to hear about the problems you had with your seahorses and I would be happy to help you figure out what may have gone wrong. I will do my best to answer the rest of your questions below.

First of all, let me just say that I see nothing at all amiss with the design and set up of your seahorse tank as described. I do not think the fault lies with the aquarium system you’re using for your seahorses.

1. Do seahorses die that quickly without the trickle filter and aerator? Should I have been told I need a backup power source to keep seahorses (we lose power for that long frequently where I am, although this wasn’t the reason in this case). I have now read methyl blue assists with the oxygen uptake. Would the one left had had a better chance if I had another tank set up so I could treat it straight away (I was just in the process of getting the ‘hospital’ tank set up).

Yes, Dymond — seahorses need high levels of dissolved oxygen in order to thrive and my best guess is that your seahorses may have asphyxiated during the power failure. Hypoxia due to low oxygen levels and/or or high carbon dioxide levels has been known to kill seahorses suddenly and without warning. This often tends to happen overnight when CO2 naturally rises as O2 levels are dropping due to the reversal of photosynthesis. Many times under such circumstances one or more of the seahorses will be followed laying still on the bottom in the morning with no other premonitory signs or symptoms of a health problem.

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 essentially consume O2 and give off CO2 instead. So in a small, closed-system aquarium, dissolved oxygen levels are typically the highest and dissolved CO2 levels the lowest just before lights out when the aquarium lights have been on all day long. Likewise, dissolved oxygen levels are normally at their lowest and CO2 levels at their highest first thing in the morning after the aquarium lights have been off all night. (The drop in pH most aquariums experience overnight is directly related to the drop in dissolved oxygen levels and the rise in carbon dioxide levels that takes place during the night.) Seahorse setups in general are especially 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. But there are also a number of other factors that affect the levels of dissolved oxygen in the aquarium, and under certain circumstances, asphyxiation in seahorses can also occur when there has been no equipment failure.

For instance, heat stress due to a summertime heat wave can rapidly deplete the oxygen levels in a poorly circulated seahorse tank. It’s important to remember that the warmer the water, the less dissolved oxygen it can hold. Elevated water temperatures increase the metabolism of your seahorses, and therefore their consumption of oxygen, at the same time that the rise in temperature is reducing the amount of dissolved oxygen in the water. That creates a dangerous situation for seahorses and may well result in respiratory distress and rapid, labored breathing, as well as contributing to asphyxia under certain circumstances. In my experience, the optimal temperature range for Mustangs (Hippocampus erectus) in the home aquarium is 72°F-75°F (22°C-24°C), and they may begin to experience heat stress if the water temperature approaches 80°F (27°C) or above for a significant period of time.

There is also an inverse relationship between salinity and dissolved oxygen. The higher the specific gravity or salinity, the less dissolved oxygen the water can hold. By the same token, the lower the salinity or specific gravity, the more dissolved oxygen the water can hold. Sometimes the specific gravity in a seahorse tank can creep up unbeknownst to the aquarist due to evaporation of the aquarium water, and the higher the specific gravity gets, the lower the dissolved oxygen levels in the aquarium will be.

A combination of these factors can be downright deadly. If a heavily planted tank is running too warm and if the specific gravity or salinity of the aquarium has risen higher than the suggested range (1.024-1.025), and the tank is undercirculated, that can sometimes be a recipe for disaster. The oxygen levels in the aquarium will be reduced as a result, and when the lights go off and photosynthesis ceases in a heavily planted aquarium, the oxygen levels will be further depleted while the CO2 levels are rising. In some cases, this can wipe out a tankful of healthy seahorses literally overnight, particularly if the tank is well stocked and houses several seahorses.

Such potential problems with hypoxia are sometimes exacerbated by a transient ammonia or nitrite spike following a heavy feeding. Such spikes are often difficult to detect with test kits because they normally clear up within several hours following the feeding. But despite their transitory nature, they may already have done their damage in the interim by affecting the seahorse’s blood and making it difficult for them to get enough oxygen. This happens because some of the hemoglobin in the red blood cells of the seahorse is converted to methhemoglobin when it is exposed to nitrogenous wastes such as the nitrite and ammonia, or excessively high levels of nitrates, and methhemoglobin cannot transport oxygen. So if there is a spike in the nitrate or ammonia levels in your aquarium following a heavy feeding, or the nitrate levels are consistently elevated, impairing the ability of the seahorses to transport oxygen through their bloodstreams, at the same time that the dissolved oxygen levels are falling and CO2 levels are rising due to the sort of factors mentioned above, seahorses are in danger of asphyxiation.

In short, Dymond, it is certainly very possible if not likely that your seahorses asphyxiated as a result of a power failure cutting off the circulation and aeration to the aquarium. Wet/dry trickle filters provide wonderfully efficient biological filtration because they support such an immense population of aerobic or oxygen-loving nitrifying bacteria, but the high oxygen demand of the biofilter itself can help deplete the dissolved oxygen levels rapidly when there is a power failure. If your water temperature is running on the high side, your seahorse system is under circulated or overstocked, or the salinity has crept up higher than normal and/or there may have been an ammonia or nitrite spikes following the last feeding of the day, such problems are even more harmful. I would not expect the invertebrates to be adversely affected in a case like yours since their metabolic demand for oxygen is so much lower than that of the seahorses.

In this instance, Dymond, your seahorse tank certainly does not appear to have been overstocked or undercirculated, and it doesn’t appear that the water temperature was abnormally high — at least, not warm enough to have become a problem under normal conditions at all. Nor do I believe that there was an ammonia spike or spike in the nitrate levels (your seahorse setup is large enough and has plenty of live rock to avoid such spikes). But the power failure during the night in the tank with high oxygen demand due to an immense population of aerobic bacteria in the biofilter was apparently enough to drop the dissolved oxygen to a critical level. In short, I think the death of your seahorses was an accident associated with the loss of power to the tank.

Here is what I would suggest to prevent such problems in the future:

(1) Take some precautions to prevent a drastic drop in the dissolved oxygen levels in your aquarium during any future power outages.

(2) Gradually reduce the specific gravity of your aquarium to around 1.022 to help increase the amount of dissolved oxygen the water can hold.

(3) Consider installing a protein skimmer for supplemental filtration as well as improved aeration and oxygenation.

(4) Keep methylene blue in your fish room medicine cabinet in case of hypoxic emergencies or almost a/nitrite poisoning.

Let’s discuss 1 and 4 in more detail below:

Power Failure Precautions for Aquarists

The primary problem for the aquarist when there is a power failure is a massive die off or tank crash due to a drop in the dissolved oxygen levels and a corresponding rise in carbon dioxide. How quickly this becomes problematic depends on the size of the aquarium and the number of fish and invertebrates it houses. The smaller the tank and the greater the number of specimens it contains, the quicker they will deplete the available oxygen and begin to die off, so with small heavily stocked tanks it’s very important to restore power as soon as possible. A larger tank with just a few specimens will have a larger margin of error before the dissolved oxygen is exhausted. But whenever there is a power outage, you should strive to provide the tank with oxygen one way or another as quickly as possible to save your biofilter and prevent losses due to asphyxiation.

Summertime heat waves and power outages happen all too often and when they happen to coincide it’s always bad news for seahorses. The loss of power shuts off your filters and airstones and protein skimmers no longer generate a bubble stream, and the resulting lack of circulation and surface agitation rapidly causes a drop in dissolved oxygen levels and a rise in carbon dioxide levels due to the respiration of the seahorses and their tankmates.

At the same time, the loss of air conditioning and elevated water temperatures that result increase the metabolism of your seahorses, and therefore their consumption of oxygen, at the very time that the rise in temperature is further reducing the amount of dissolved oxygen the water can hold. This creates a doubly dangerous situation for seahorses and results in rapid, labored breathing, hypoxia, and eventually death by asphyxia or suffocation.

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, seahorses are thus especially vulnerable to low oxygen levels and asphyxia.

Power failures are a common problem for aquarists who happen to live in hurricane country or tornado alley, and of course, brownouts are pretty common during summertime heat waves when everybody’s trying to run their air conditioners at the same time. Freezing rain and ice during the wintertime can be just as troublesome when ice storms bring down tree limbs and power lines and knocked out the electricity. In a pinch, you can make an effort to manually aerate and oxygenate the tankby scooping pitchers of water and pouring them back into the aquarium from a height of 6 inches or more, but you are really fighting a losing battle that way and it will positively wear you out if the power is out for any length of time.

Another option you can consider in such an emergency is to add hydrogen peroxide (H202) to the aquarium to increased the levels of dissolved oxygen rapidly. A 3% hydrogen peroxide solution is useful during the hypoxic emergencies that may occur in an aquarium during a power outage, or when the primary filter fails overnight, as explained below:

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Dosing tank with hydrogen peroxide to boost oxygen levels

There is also another trick you can consider for raising the dissolved oxygen level in your aquarium quickly by adding a small amount of ordinary hydrogen peroxide (H202) at the right concentration to your aquarium. Hydrogen peroxide can be use as a treatment of acute oxygen insufficiency at a dose of 0.25 ml of a 3% H2O2 solution per litre of water, which is equivalent to adding 1 ml of a 3% hydrogen peroxide solution per gallon of water.

Remember to allow for the amount of water that is displaced by the aquarium substrate and decorations when calculating how many milliliters of a 3% hydrogen peroxide solution to add to your aquarium. Be careful not to exceed the recommended dosage since adding too much of the hydrogen peroxide can be harmful. This is a one time emergency procedure for use in a crisis situation — do not add any additional hydrogen peroxide to the aquarium after the first dose.

Contrary to popular belief, in water with relatively low organic content, the concentration of Hydrogen peroxide does not decrease significantly. Of course, any increase in organic loading will change this factor, but the bottom line is that Hydrogen peroxide does not break down as quickly as some may think. Water changes are required after treatment.
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Aside from such stopgap measures, better solutions are available if you prepare in advance for the next brownout or prolonged power outage, as discussed below.

To begin with the obvious, if you live in an area that’s prone to power outages, investing in a backup generator is something you may want to consider. But there are also a number of other less costly measures that can help the aquarist and his fishes make it through a power outage without suffering devastating losses. For example, here are some excellent tips from Dan at the org regarding how hobbyists can cope with power outages:

"Some possible options besides a generator are:

Battery operated pumps. Some of the bait pumps that use 2 D cells can
run for up to 4 to 5 days and can drive 2 to 3 airstones. Besides
aerating the tank, it also helps to aerate the biological filter if
possible.

Computer Uninterrupted Power Supply (UPS). They can be real handy. If placed inline with your equipment it can seemlessly keep stuff running for short durations or
drive air pumps for quite a while.

Deep cycle marine batteries with an inverter. During the hurricanes,
we pulled the batteries and the inverter off the boat and ran quite a
bit of equipment off these for 24 hours.

For short term unexpected outages, battery operated pumps and/or
computer UPS are probably the most economical answer. For long term
outages, such as a hurricane, a generator will pay for itself the first
time it is used.

Another consideration for long term outages, is to have plenty of water
available. Often long term outages lead to water availability issues."

Dan

The decrease in dissolved oxygen levels is not the only threat to your aquarium when there is a power failure. You must also be aware of filters and equipment that doesn’t automatically restart once the power comes back on, and if you have a sump or refugium connected to the main tank, water siphoning our the main tank can also be a huge headache, as Al explained in this previous post:

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I have so many power outtages here and often of such long duration that I
feel like I`m living in a third world country so I`m way too familiar with the quandary, "WHERE
DID ALL THIS WATER C0ME FR0M?" in the aftermath of a power failure.

If you use a tank/refugium combination that are on different levels, water
siphoning down out of your main tank through air hoses or the water pump return
hose will be a problem. They do sell air check valves that prevent this from
happening with air hoses, or you can make a loop in the air line that remains
positioned AB0VE the main tank`s water line which will prevent a gravity fed
back-flow through the airline.

Water siphoning back into the refugium from the main tank through the water
pump or other inlet/outlets can be avoided by:

a) placing the return hose outlet to the main tank AB0VE the water line.
This will cause a break in the water column should the pump fail and it also
creates greater surface turbulence during normal operation

b) place the pump return hose near the surface of your main tank and make
sure your refugium/wet-dry filter can contain the excess water that could siphon
off the main tank before the level drops sufficiently to break the water
column.

c) if your tank is bored out and fitted with bulkheads anywhere lower than
the top few inches of the tank, get some extension hose or PVC piping to make a
loop for the inlet that is above the water line in the main tank and a loop
that is just below the water line for the overflow/outlet. These loops will
limit the water lost out of the main tank in the event of a power failure.

Another annoying problem is caused by hang on filters and other magnetic
impeller driven devices that won`t restart on their own <as well as many canopy
lights> after a power failure. Some brands of hang ons need to be *primed*
before they will start moving water again, others need their impellers coaxed a
little. Turn your tank power off for about 20 minutes and test where you`re
likely to have problems.

Al
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Methylene Blue for Relieving Respiratory Distress

Remember that good old methylene blue can work wonders in cases of hypoxia and respiratory distress. Commonly known as "meth blue" or simply "blue," this is a wonderful medication for reversing the toxic effects of ammonia and nitrite poisoning, or exposure to elevated nitrate levels. Methylene blue transports oxygen and aids breathing. It facilitates oxygen transport, helping fish breathe more easily by converting methemoglobin to hemoglobin — the normal oxygen carrying component of fish blood, thus allowing more oxygen to be carried through the bloodstream. This makes it very useful for treating gill infections, low oxygen levels, or anytime your seahorses are breathing rapidly and experiencing respiratory distress. It is the drug of choice for treating hypoxic emergencies of any kind with your fish. However, methylene blue will destroy nitrifying bacteria so it should be used in a hospital tank or as a brief bath or dip only (if used in an established aquarium, it will impair the biological filtration and the tank may need to be cycled all over again).

Here is some more information that may be helpful if ever need to treat with methylene blue, Dymond:

If you can obtain the Kordon brand of Methylene Blue (available at most well-stocked local fish stores), there are instructions for administering it as a very brief, concentrated dip are as follows:

For use as a dip for treatment of fungus or external parasitic protozoans and cyanide poisoning:
(a) Prepare a nonmetallic container of sufficient size to contain the fish to be treated by adding water similar to the original aquarium.
(b) Add 5 teaspoons (24.65 ml) per 3 gallons of water. This produces a concentration of 50 ppm. It is not recommended that the concentration be increased beyond 50 ppm.
(c) Place fishes to be treated in this solution for no longer than 10 seconds.
(d) Return fish to original aquarium.

When you administer such a dip, hold the seahorse in your hand throughout the procedure and time it closely so that the dip does not exceed 10 seconds.

And here are Kordon’s instructions for administering the methylene blue in a hospital tank if longer-term treatment seems appropriate to reverse more severe cases of nitrite poisoning and ammonia toxicity:

As an aid in reversal of nitrite (NO2-) or cyanide (CN-) poisoning of marine and freshwater aquarium fishes:
(a) Remove carbon filter and continue to operate with mechanical filter media throughout the treatment period.
(b) Add 1 teaspoon of 2.303% Methylene Blue per 10 gallons of water. This produces a concentration of 3 ppm. Continue the treatment for 3 to 5 days.
(c) Make a water change as noted and replace the filter carbon at the conclusion of the treatment.

See the following link for more information on treating with Kordon’s Methylene Blue:

Click here: KPD-28 Methylene Blue
http://www.novalek.com/archive/kpd28.htm

If you obtained a brand of methylene blue other than Kordon, just follow the instructions the medication comes with. Remember that methylene blue will destroy the beneficial nitrifying bacteria in your biofilter, so it should only be administered in a hospital tank or a separate dipping container.

In short, it’s possible that prompt treatment with methylene blue may have helped the female to revive, which he may already have been too far gone to respond.

2. Maybe I didn’t put chorine removal in all the replacement water buckets (but it was 6hrs before they died – is this possible) and they had chorine poisoning.

No, sir, I don’t believe that failing to use a chlorine neutralizer in some of the water you added to the aquarium killed the seahorses due to chlorine poisoning. Chlorine dissipates fairly quickly and the amount that could have entered your aquarium in this way is fairly negligible considering the size of the aquarium and the amount of water you exchanged.

3. Could the clean up cause an ammonium spike I didn’t pick up. Would they die straight away from this or would it take 6hrs?

Transitory ammonia spikes are always a possibility and a concern in small closed-system aquariums following a heavy feeding, but I don’t believe that this was a problem in your case, Dymond. Your seahorse tank is large enough to provide a considerable margin for error with regard to such spikes, and the efficient filtration provided by the trickle filter and live rock should be sufficient to prevent such ammonia spikes in an aquarium that is not over stocked or under circulated. Sometimes aggressively vacuuming the gravel or live sand in the aquarium can momentarily disrupt the biological filtration, but that should not have been a concern with your aquarium system. In your tank, the trickle filter and live rock are the primary means of biofiltration, rather than the substrate that might have been temporarily disrupted by an overzealous cleaning session.

Ammonia poisoning can kill relatively quickly or very gradually over a period of several days depending on the level of ammonia exposure and the length of time the seahorses were exposed. The most obvious symptoms of ammonia poisoning are a loss of equilibrium, hyperexcitability, increased respiration and oxygen uptake, and increased heart rate. At extreme ammonia 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.

In significant cases, you will often see the affected seahorses lying prone on the bottom unable to right themselves at all for extended periods, blindly bumping into objects on the walls of the aquarium in complete disorientation, and going into actual convulsions, accompanied by severe respiratory distress.

Ammonia poisoning is completely reversible providing the seahorses weren’t exposed to toxic levels for too long, and the best first aid you can provide for ammonia poisoning is to immediately transfer the seahorses into clean, well-aerated saltwater with zero ammonia and zero nitrite, which you have already accomplished when you acclimated the seahorses to their aquarium.

As we have been discussing, exposure to moderate levels of ammonia and nitrite (or excessively high levels of nitrates) can change the normal hemoglobin in the seahorse’s blood stream to a form (i.e., methhemoglobin) that is no longer able to transport oxygen. If this becomes severe enough, it will leave the affected seahorse starved for oxygen, which makes it very weak and fatigued. As a result, the affected seahorses may detach themselves from their hitching posts periodically and rest on the bottom, unable to exert themselves in their weakened condition. As you can imagine, being deprived of oxygen really wipes them out in terms of loss of energy and stamina. And it also results in respiratory distress, and rapid, labored breathing as they try to oxygenate themselves and compensate for the lack of normal hemoglobin.

One of the properties of methylene blue is that it can reverse this process and convert the methhemoglobin in the red blood cells back into normal hemoglobin, which can then pick up and transport oxygen again as usual. That’s why it is so helpful in relieving shipping stress and treating ammonia exposure and nitrite poisoning. For this reason, you may want to pick up some methylene blue at your local fish store and keep it on hand in case it is ever needed (the Kordon brand of methylene blue is best, in my opinion).

The usual criteria for determining whether or not methylene blue is needed to help seahorses recover from exposure to high levels of ammonia is their respiration. If the seahorse has labored breathing — huffing or rapid respiration — then methylene blue is called for. Likewise, if the seahorse is experiencing convulsions or it’s behavior otherwise indicates it is suffering from more than temporary disorientation and loss of equilibrium, such as lying prostrate on the bottom, unable to right itself again at all after two or three hours have passed, it may benefit from methylene blue to assist its recovery.

However, Dymond, as I said, I don’t believe that ammonia poisoning or a severe ammonia spike was involved in this instance…

4. Is really the combination of the tank shift, the clean and then the lack of oxygen? Would they feed and hunt after the clean and looked brightly coloured if the clean had been too much. I am thinking I should just stick to the live rock – then I read other sites that said I should never should have live rock with seahorses. Anyway. Hope someone can help.

I don’t believe that the aquarium cleaning and/or the tank shift were the culprits in this case, sir. Rather, I suspect that the loss of power to the aquarium resulting in a rapid decline in dissolved oxygen and a rapid rise in CO2 levels during the night was in itself sufficient to asphyxiate the seahorses. This was an accident and you should be able to prevent a recurrence, so I would not let this regrettable incident discourage you from trying seahorses again.

Some seahorse keepers do indeed frown on live rock, primarily because of the unwanted hitchhikers that may enter aquarium along with the live rock. This includes such pests as Aiptasia rock anemones, mantis shrimp, and large bristleworms, all of which can sometimes be problematic for seahorses. But there are plenty of ways to include live rock in your seahorse setup so that it benefits from all of the advantages live rock provides (stability, shelter and natural decor, denitrification ability, and additional nitrification) while excluding the unwanted pests. Personally, I am a big proponent of pest-free live rock and a seahorse system. If anything, I would advise you to increase the amount of well-cured, debugged live rock in your seahorse setup in the future.

Before you consider abandoning seahorses, Dymond, I would like to invite you to participate in the Ocean Rider seahorse training program. As I have discussed on this forum many times, the training program is a correspondence course conducted entirely via e-mail that is open to any and all interested hobbyists and is entirely free of charge. It is very comprehensive — much more so than any guide books about seahorses that are currently available — and completing the training course will give you an excellent understanding of the specialized needs and aquarium requirements of seahorses. The very first lesson includes a detailed discussion of the pros and cons of using live rock in a seahorse setup, and by the time you have completed all 10 of the lessons you should have a very good idea of whether or not you can be a successful seahorse keeper.

If you would like to give the training program at try, please contact me off list ([email protected]) with a brief e-mail including your full name (first and last) and I will get you started with the first lesson right away.

Best wishes with all your fishes, Dymond. Please accept all my condolences for your losses when the power to the aquarium was cut off.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support