Has hypo been debunked? Old articles say it works, newer stuff calls it outdated.
First, as a newbie, I want to thank everyone here first for their great advice as I've jumped into this hobby over the past year. I consider myself a voracious consumer of information, but the more I get into this hobby the more I realize what I don't know! I read lots of stuff, and I usually find an answer to my question, so I feel no need to post. The stickies are a wonderful thing!
However, I thought I would chime in about what appears to be facts, but also some myths about hypo, based on what I have learned over the past year or so. I don't have access to the full research, but I think I have a grasp on what is known (through peer reviewed science) as posted by many of our experts here. As background, I believe I have successfully used hypo as ich treatment, having had a severe outbreak that killed over half my livestock, and post-treatment have not seen any signs of ich. Of course, I can't be 100% sure it is gone, but one of my survivors is a blue hippo tang, often referred to as an "œich magnet". If I still had ich, my assumption is I would see some type of symptom. Of course, I may be in the camp (not as a volunteer!) of those who claim to successfully manage ich and don't understand the need to eradicate it from an aquarium.
1. There is a scientific basis for hypo being an effective treatment. However, in one instance, research discovered a particular strain of ich (I believe off the coast of Taiwan) that was resistant to hypo. Is this strain present in your current outbreak? Probably impossible to determine, but I would think highly unlikely. Are there other strains immune to hypo? Maybe.
2. Except for the strain mentioned above, I believe all failures using hypo to treat ich are anecdotal. One may guess why it didn't work, but I don't believe there are any fully researched reasons. In my opinion, lack of proper execution is probably more the cause than having a strain that is hypo resistant.
3. Many recommendations state how critical and difficult it is to hold the salinity at the therapeutic concentration, and the need for an ATO during hypo treatment. The fact (mathematically based) is this shouldn't be a concern under normal conditions unless you have constant extreme water loss from evaporation. The smaller a system (and I'm talking nano) the harder it is to regulate. You state you have 170 gallons in your system. Let's be ultra conservative and says your LR, equipment, etc. reduces this to 100 gallons actual water. Given the resolution of your refractometer (to the third decimal place), you would have to lose over 5 gallons of water before your reading went from 1.009 to 1.010, detecting a change in measured salinity! (If anyone wants details on how I mathematically arrived at this, I can provide the details). Unless you are losing this much water per day (4-5 gallons), it should be fairly easy to hold at the therapeutic salinity levels.
4. It has been stated that if your salinity does increase by only 0.001 you must restart the clock. I don't believe the research did a series of tests (i.e. at 1.008, 1.009, 1.010, 1.011, etc.) and found a big difference between 1.009 and 1.010. If my assumption is wrong, please correct me. The ich parasite, although a relatively lowly organism, is still a very complex creature. I don't think its reaction to such small differences would be significant. If I were to predict what research would show, an outcome is more likely be something like 99.20% don't survive at 1.010, and 99.99% don't survive 1.009, rather than only 5% are killed at 1.010 versus the 99.99% at 1.009.
5. When I did hypo, I was surprised to note a single salt crystal sign of ich on a fish several weeks after I started hypo. Bottom line is don't start the 72 day clock until after the last symptom is gone. The first day you reach the therapeutic level is not necessarily when you start counting. I recommend you be very observant of each fish, looking for the slightest symptom of infection. I conjecture this may one of the reasons why hypo treatment failed.
6. Only conjecture on my part, but when an ich cyst hatches, I don't think the theront instantly "˜explodes' under hypo conditions. It may be milliseconds, seconds, or even minutes. If a host is right there and it can attach immediately, then the parasite may survive. The last fish I saw in my tank with ich symptoms was a green chromis that would sleep deep in the chambers of my LR. My ich infection was severe enough that I probably had enough cysts producing enough theronts that I need a couple of cycles to wipe them out until all the theronts would die before finding a host.
7. When I was lowering my salinity, I noticed in the beginning it would bounce back up (by 0.001) after 24 hours. I believe this was because it took a while for the water trapped between sand molecules in my sand bed to come to equilibrium with the rest of the water in the tank. As this high salinity water mixed in, it would raise the average salinity of the system. I would think the same is true for the saltwater within the pore spaces of the living rock. I would also guess that it would take far longer for this water to equilibrate with the surrounding water. Could it take days or weeks? I don't know. I bring this point up, because you measure salinity in the main body of water. Could the local salinity (i.e. where the ich cyst is hatching and the host is present) be different and take longer to come to the same level as the main water being measured? I think possibly, and maybe why the chromis had ich symptoms three weeks after hypo started, as this indicated the theront had survived and was able to attach to a host.
8. The 72 day treatment period is based on a study that showed that even though the majority of cysts release after 4 to 8 days, the observed range was 3 to 72 days. Could it be longer? Sure, given a large enough number of cysts, statistically it could happen, but the risk it probably low. Just like my discussion on salinity, day 72 is not a magic number. The statistics between 71 and 72 (or 73) are probably pretty small. It is not as if the tomont sets an alarm clock for 71 days, and bang, you nail it by going 72. For example, I think we have far more research on the human gestation period. We should be able to predict a due date down to the hour, maybe even the minute. Speaking from experience, I'm glad I didn't fill in my calendar with other activities on the day before or day after my baby's due date! (In reality, my first child was born 2 weeks overdue.)
Bottom line is that hypo seems to be discounted as a treatment, but failure seems to anecdotal, with exact causes unknown. Success can't be guaranteed, but should be considered as an option. It all comes down to potential risk and reward. If I am wrong, or anyone disagrees with what I have summarized above, I welcome the feedback, as I do not want to be distributing wrong advice.
