Pouch emphysema (PE) is a relatively common issue which hobbyists have seen occur in male seahorses. It is caused by gas trapped within the pouch of the male. When it occurs, the seahorse becomes positively buoyant. The amount of gas trapped, and the strength of the seahorse, will determine whether the seahorse will lose the ability to swim to the bottom of the tank and hitch. In some cases the male seahorse will be trapped at the top of the tank. Some seahorses seem to handle this better than others. If the seahorse becomes really stressed over losing the ability to swim properly, or cannot reach the food, it will stop eating. I have yet to find any scientific research that definitively describes the cause of Pouch Emphysema. Fortunately, we have found that PE is a preventable malady.
Manual Pouch Evacuation can expel the gas, so the male can swim normal again. Even though this is a relatively simple process, it is quite scary for the novice who is performing the procedure for the first time. The procedure is to grasp the seahorse from behind, keeping him underwater, and tilting him backwards at about a 45 degree angle. Next, taking a blunt object such as a catheter, bobby pin, etc., and gently inserting it slightly into the pouch opening. Then pulling the blunt object slightly to one side opening the pouch, and using the hand holding the seahorse to gently manipulate the pouch so the gas moves in the pouch. The bubbles can be seen exiting the pouch. Gentle manipulation will ensure that all the gas is out. In Re-Occurring PE, a male will continue to get gas in the pouch multiple times.
Re-Occurring PE can be a big problem for many hobbyists. In this case, the gas is evacuated from the pouch, but within a short period of time the male gets PE again. The process repeats itself over and over. Unless stopped, the stress on the male can eventually cause him to succumb and perish. Sadly this ailment prevents some hobbyists from getting males seahorses in fear of having to deal with the dreaded Pouch Emphysema. It has also caused some to give up on keeping seahorses. Fortunately, it is a preventable malady.
Background and History
When we first started with seahorses back in 2003, there were many theories of what causes PE, such as bubbles in the tank, protein skimmers, excess CO2, infection inside the pouch, etc. Some of these (ie. protein skimmers, air bubbles) have since been proven false.
At first we had our share of issues with Pouch Emphysema. We had many seahorses, and found that we had to do Pouch Evacuations on one or another often. While we became quite good at the evacuations, finding a preventative measure was key. We also had our share of Subcutaneous Gas Bubble Disease (SGBD). At that time the most widely accepted recommendations were to have low flow in a seahorse tank and to avoid using a protein skimmer. Keeping seahorses at tropical tank temperatures was also widely accepted.
Most of our systems at that time compromised of 8 to 10, 30 gallon tanks, on a single sump. We used blue bonded media to catch larger particles that entered the sump, and had a 20 micron filter inline on the return to the tank, which was changed daily or every other day. We also used K-1 Kaldness media in a homemade bio-reactor for biological filtration.
We had purchased a Protein Skimmer, but based on the advice on all of the message boards, we were not using it. We knew we needed in to increase the mechanical filtration in our systems to remove organic matter. So one day, we decided to go ahead and try the protein skimmer. After a short period of time, instead of increasing the issues with PE and SGBD, we were surprised to see the issues decrease. So we got another protein skimmer to try on another system. Similar results convinced us further. The incidences of the PE & SGBD continued decreasing, and we soon had a protein skimmer on every system.
We began to feel pretty good about ourselves. We had reduced the PE and SGBD issues in our male seahorses! The issues were still occurring, but not nearly as much. Increased filtration helped! We began to wonder if it went beyond a mere external gas issue, and think that maybe it was more directly related to water quality. Our basic parameters, (Ammonia, Nitrates, pH etc.) were all correct, but we knew we had a lot of suspended solids and dissolved solids in the water. So we decided to replace the 20 micron filters with 1 micron filters, and clean up the water even more. After 2 days, we quickly abandoned the 1 micron filters. They were becoming too clogged, too quickly, and in some cases within 1 to 2 hours the flow rate was dropping too much. Constantly changing the filters was not an efficient option, so we then experimented with 10 and 5 micron filters. We finally settled on 5 microns, as we were able to go 24 hours before changing them. Once again, we saw a decrease in the amount of PE and SGBD. So we began to develop the theory that excess organic matter may be the culprit.
We continued looking for ways to further reduce the organics. One of the ideas we tried was using a filter sock, instead of just the Blue Bonded Media. In the end, we settled upon 100 micron filter socks. We didn’t see a dramatic decrease in the PE or SGBD, but there seemed to be a slight decrease, and we noticed our sumps were staying cleaner and the cartridge filters didn’t clog up as quickly.
One day, we had a batch of H. erectus fry that were several days old, that unfortunately were crashing. We had some that had visible air bubbles and some that were just so weak, they were trapped in the survace tension. Most were not eating. This was at the end of the day, where we would not be adding any more Artemia. So, I decided to turn up the return flow. My counterpart almost had a fit, because the fry were being blown all over the place. My thought was that we needed better water quality in the tank, and the slow flow rate we had wasn’t enough. I explained that we would probably lose this batch anyway, so trying something new was worth a shot. I was fully expecting to have to siphon out a lot fry off the bottom of the tank in the morning. Instead, when we turned the lights on in the morning, there were very few floaters. The fry looked amazingly better. We ended up salvaging the entire batch of fry. This made us rethink our position on flow rates in seahorse tanks, and consider that higher flow may be the way to go, despite the widely accepted belief that seahorses needed low flow.
So we began experimenting with flow rates. Over time, we found that seahorses not only thrived with higher return flow rates, they were more active and there were less disease issues including PE.
While researching another subject, I came across a paper that described seahorses ejecting organic matter during the snick, and indicating that their rudimentary digestive system was inefficient at digesting food, leaving almost ¼ of the food undigested. Sadly, I was working on something else and forgot to save or bookmark the paper, but the idea stuck with me. The large amounts of food seahorses eat, and their inefficiencies in consuming and digesting leads to a lot of organics into the water. Excess organics in any environment creates problems, and unfortunately, suspended and dissolved organics are not always obvious. Hobbyists don’t have the means to test for it.
Probiotics seemed like a good idea to help reduce the organics. If we introduced good bacteria to feed upon them, this would reduce the opportunity for bad bacteria. Sadly, at the time, there weren’t many probiotic products available, and many of them had to be “cooked”. This involved adding the bacteria to a vessel, and feeding it carbon until the count got high enough to add to the tanks. This added to our already overburdened workload. Most of the bottle products were enzymes, or had nitrifying bacteria that were labeled probiotics. There were several products overseas that I had read about, that had good reviews, but they had strains of bacteria that I could not import. Finally, I tried Inve’s Sanolife MIC. This product was easy to use, and after several months of use, we once again found a decrease in health issues, including PE and SGBD.
We also tried experimenting with Hydrogen Peroxide as a means of reducing organics. I happened across a thread in a Fresh Water Planted Tank forum, where someone discussed using an Oxydator in their tank. The Oxydator is a device from Germany that slowly releases minute amounts of peroxide into the water, which increases oxygen saturation, and in the process oxidizes organic matter. Our experiments found that this worked quite well in a normal display tank with appropriate stocking densities, but not well in our overstocked production systems. Trying to manually dose peroxide in a system can be done, but requires accurate math in dosing and proper testing to ensure that you have the right levels. Overdosing will impact the biological filter, so a lot of monitoring and testing is required. While it can be useful in certain situations, it was not a good fit into our long term management of larger systems.
By 2010, we had pretty much fine tuned our systems, our stocking densities and our husbandry. It had become very rare for us encounter Pouch Emphysema anymore. Our inventory of sexually mature seahorses can vary from as few as around 100, to multiples of 100, and we rarely saw more than 2 instances of PE in a year. In 2012 we discarded the last of the Diamox we had on hand as it had expired, and we hadn’t used it in a long time. We haven’t had to use it since.
We were doing quite well at preventing PE but we were still seeing a lot of instances where hobbyists were still encountering this issue, both in the forums and calls we receive to our help desk. We get a lot of calls for help with seahorses. Some of these calls are from customers, but the overwhelming majority is from folks who bought their seahorses elsewhere, and did not get good advice on setting up their seahorse tanks. Or the seller did not provide ongoing support after the sale. At any given time, I am always helping at least one hobbyist, if not several, to solve an issue. When I am speaking directly to the hobbyist, I am able to get a complete history and dig deeper by asking questions. I normally get much more information than what is given in an email, posted on message board or what is given in text messages. Over time, as this data is collected, one can begin to see patterns and trends.
Much of what we found was similar to our own situation. Focusing on reducing the organics in the tank seems to solve the issue. This was especially true in cases of Re-Occurring PE.
1. Using live rock as their only means of filtration. Live rock is a great biological filter, but it is a biological filter and not a mechanical filter. Organic matter must be eaten by something and converted to ammonia for the live rock to do anything. Mechanical filtration can remove it before it is eaten and reduce the biological load. Adding mechanical filtration helped.
2. Adding, upgrading or proper maintenance on a protein skimmer. Adding a protein skimmer is a big help on a seahorse tank. We also found that many people were waiting until their skimmer cup filled before emptying it. Once the riser tube gets junked up, the skimmers performance drops. Depending upon design, this can be as much as 25 to 50%. By cleaning the skimmer and empty the cup once the riser tube gets dirty, more skimmate is collected.
3. Flow Rates. We have often found that too little water movement in the tank allows things to settle. Increasing the flow rate to a level that keeps organic matter suspended until the mechanical filter can remove it helped. Also the rate of water moving through the mechanical filter was often not enough. Increasing it, allows more water to be filtered as it passes through the mechanical filter. As a general rule, we found that flow rate though the filter needs to be at least 10 times water volume of the tank per hour.
4. Temperature. This doesn’t seem to increase or prevent PE, but what we did find was that in warmer tanks it would happen sooner than in cooler tanks.
5. Water changes. Those who did larger, more frequent water changes had less incidence of PE issues.
6. Over stocking. We also found that folks who had a higher ratio of seahorses per water volume had a higher incidence of PE.
7. Feeding. We never worry about over feeding seahorses but we do worry about over feeding the tank. This usually isn’t a problem as most folks have a tendency to under feed their seahorses. But on occasion we have seen this become part of the issue. Rinsing the frozen food under tap water for a minute or two can remove a lot of loose excess nutrients. In heavily stocked tanks that require a lot of food, this has helped make a difference.
8. One very interesting thing we found that certainly helped confirm our thoughts was, in cases of Re-Occurring PE, we would have the customer move the seahorse to a hospital tank with clean new saltwater. Since there wasn’t a biological filter, large daily water changes were necessary to keep the ammonia at bay. In many cases, this alone resolved the issue. There were also instances in which the seahorses were treated with both Diamox and Antibiotics in pouch flushes. However, once the seahorse was re-introduced into the display tank, it would resume having PE issues. Clearly something was wrong in the display, and when we would finally figure out the source of the excess organic buildup, and take the corrective action, the PE issues would disappear.
By applying the information from the above examples, we were able to assist the vast majority of calls with Re-Occurring PE. But, we still had an occasional hobbyist that continued to have issues. After going back and carefully examining the data, we found that those we weren’t able to help had either a crushed coral/gravel substrate or a canister filter. At first this was puzzling, as we knew of folks who had either of these, but did not have PE issues. After taking another hard look, we found that those who didn’t have issues where what we considered “hard core enthusiasts”, who did lots of maintenance and were always on top of their tanks. The people with the issues typically had a single display tank, and were mostly interested in watching the tank, but not maintaining it. In fact, many had a maintenance company handle the maintenance for them. The pattern that we began to see was that there were no issues in the beginning, but after several months, usually 9 to 12 or so, PE issues began to crop up. Crushed coral/gravel beds can build up with detritus over time due to the spaces between them. When these people removed the crushed coral or gravel, and replaced it with sand, the PE issues disappeared. While canister filters can act as a great mechanical filter, they are out of sight, out of mind in many cases. Human nature kicks in and they end not getting cleaned as often as they should. The solution here was to use a different filter, or do proper maintenance.
Today, our success rate in helping folks resolve re-Occurring PE issues is almost 100%.
Treating Re-Occurring Pouch Emphysema
Some recommend flushing the pouch with Diamox (Acetazolamide) . Others recommend flushing the pouch with both Diamox and an Antibiotic. We have found that we have had just as much success flushing the pouch with clean new saltwater as we did with the either of aforementioned flushes. In most cases, just moving the seahorse to clean new saltwater, and giving it some time, would result in the issue resolving itself.
Prevention of Pouch Emphysema
Our recommendations are for the masses. Folks who want to set up a tank with the minimum amount of effort, and keep it going with the least amount of issues. Folks who follow these guidelines are not only less likely to see Pouch Emphysema, they are also less likely to see many of the other maladies that afflict seahorses. Yes, there are some who do things differently with success. If you are an experienced aquarist, endlessly fiddling with and maintaining your tank(s), or have a more robust filtration scheme, you may succeed without following these guidelines. But, if you have issues, compare your setup to the recommendations, and consider some changes.
Our recommendations for preventing Pouch Emphysema and stopping Re-Occurring Pouch Emphysema are as follows:
1. Tank Size & Stocking Density: 30 gallons minimum for 1 pair and an additional 25 to 30 gallon for each additional pair of seahorses.
2. Substrate: Sand or bare bottom. Avoid crushed coral or gravel.
3. Water Flow: There are two areas to consider here. First is the amount of water movement in the tank. This should be enough to keep organics in suspension so the filters can remove it. As a starting point we recommend approximately 10x the tank volume, and adjust up or down from there depending on what the seahorses can comfortably handle. This can include a return from the sump, airlines, HOB filters, Power Heads, etc. Second, is the amount of water moving through the mechanical filter. The more water that moves through the filter, the more it is able to remove. Again, our starting recommendation is about 10x the volume of the tank.
4. Biological Filtration: This doesn’t appear to directly impact the occurrence of PE, but having biological filtration in addition to the mechanical filters allows one to thoroughly clean the mechanical filters without impacting the biological filtration of the tank.
5. Mechanical Filtration: Should be of some design to remove particulate matter. The tighter the filtration, the more it can remove.
6. Protein Skimmer: This is technically part of the mechanical filtration, but I listed it separately due to its importance. A good performing protein skimmer is crucial, and we recommend oversizing it. Protein Skimmers on seahorse tanks pull out a lot of gunk! Protein skimmer should be emptied and the riser tube cleaned anytime the riser tube gets dirty, as this effects its performance.
7. Temperature: This doesn’t seem to cause Pouch Emphysema but we have noticed that warmer tanks seem to have issues sooner than cooler tanks.
8. Maintenance: Exactly how much maintenance a tank needs and how often will depend upon both how it is setup and the stocking density. At a minimum, we recommend checking the mechanical filtration weekly.
9. Water Changes: There is no single correct answer here. Everyone seems to have a different view point. Some recommend small frequent water changes, while others recommend larger, but less frequent water changes. We do the later with our tanks. Exactly how much and how often will depend on the setup and the stocking density.
10. Clean Up Crew: A good clean up crew will consume left over food in the aquarium. Nassarius Snails, Peppermint Shrimp and Blue Leg Hermits are a good starting point. There are others that can be added, just check with tankmate guides for seahorses to ensure they are safe with seahorses.
11. Feedings: The amount of food to feed per feeding is the amount that the seahorses will eat. Some adjustments of the amount fed may need to be done periodically as the seahorses demand increases or decreases. If possible, keep food from going behind the rock and other things where it just sits. A feeding station can help with this, as well as target feeding. We also recommend rinsing the frozen food under tap water until the water runs clear. For small amounts of food, this would take about 30 seconds. Placing the food in a brine net is an easy way to do this. Also we do not recommend trying to put additives on the frozen food, as most of this washes into the tank contributing to the organic load.
The thought of encountering Pouch Emphysema can be quite scary to seahorse owners, or anyone wanting to start their first seahorse tank. With proper setup, tank maintenance and stocking densities, it is largely preventable. Enough so, it should not cause one to avoid getting a male seahorse. We have many customers who have followed the above guidelines that have never had to deal with PE. We also have many customers who changed their setups to the above guidelines that have eliminated PE issues. PE should no longer be a reason for male seahorses to be avoided in the hobby.