What should you know about Ammonia NH3???
So from past articles and discussions at our club meetings, I hope you have a better understanding of how stress to our koi shortens their life span and reduces their growth with subpar coloration. With all other things being equal your koi normally get bigger each year placing a larger ammonia load on your pond filter, which can lead to an increase in the residual levels of pond ammonia. This results in added stress which can lead to the above mentioned items plus increased illness/disease and loss of koi. Strange as it may be, I think of ammonia sort of like diabetes in humans in that both can demonstrate harmful effects on just about any part or system of the physical bodies in question and both can cause serious problems short term and long term collectively both leading to pre-mature death!
Yes, this is a serious water quality issue that needs your attention and constant vigilance. While I cannot cover the subject adequately here, I hope to get you started thinking about it and what’s going on in your pond and your koi with respect to ammonia. So let’s get started.
Ammonia is the number 1 waste product of koi and is said to be excreted from your koi’s gills for about 75% of total production, while the remaining 25% comes from the kidneys. They are always breathing and as they get larger the production of ammonia is exponential – so a koi growing from 6 inches to 12 inches does not now excrete twice the ammonia but closer to 3 times as much as when it was 6 inches. At the same time, any organic matter in your pond that comes from a protein source will release ammonia as it decays in your pond (more on this later).
To make matters worse ammonia is more toxic to your koi as the pH levels in your pond go up starting around 7.3 and at above 8 just about all ammonia will be in its de-ionized form and very toxic to your koi. Why you ask – at pH below 7.4 ammonia NH3 will start to ionize (pick up a hitching H-ion) and become ammonium or NH4. To put it simply it came out of the koi as ammonia NH3 but at a pH below 7.4 there is an abundance of extra hydrogen ions in the water looking for a home and NH3 becomes NH4. Now the important physiological fact – as NH4 it will not cross the gill membrane and re-enter the koi causing ammonias (ammonia poisoning). This is why in my opinion that any level of detectable ammonia (even trace – below 0.25ppm but not zero) in your pond needs to be addressed as long periods of even low level exposure is not without its consequences. Koi stress caused by ammonia will lead to gill hyperplasia (extra fluid around gill tissue – reduced oxygen absorption) and caustic burned gill tissue which, just to make matters worse at the same time, is a reduced immune response. Or as Dr. Johnson DVM has written “…depress the immune system (via the cortisol stress-response on vitally important immune fighter cells).” Yes, there is a chart based on pH/Temp/and your NH3 reading that will tell your toxic un-ionized ammonia NH3 level.
Now to the “more on this later” above remark. Crazy as it may seem, your feeding practices may add to the pond ammonia problem. First, any undigested food excreted (nice word for koi poop) will add to the protein organic decaying matter in your pond while providing an additional food source for the disease causing bacteria and a lot of other things growing in your pond. It’s the excess protein you may be providing that is ammonia producing. When your koi don’t use or need the protein for growth or reproduction purposes then your koi will use the extra protein in the diet as an energy source instead of the available fats and carbs. When proteins are metabolized a resulting byproduct is ammonia due to protein having a nitrogen component. When a koi uses fats and carbs for energy no ammonia is produced as a byproduct. Dr. Nicholas Saint-Erne uses the term “… protein-sparing effect” when fats and carbs are utilized as an energy source. This may not be a major point for you but as pond size goes down and fish load goes up (along with other factors) this could be a larger player toward ammonia levels in your pond.
I would suggest doing weekly ammonia testing for established ponds. Koi suffering from ammonia poisoning will most often develop redness at the ends of fins followed by visible red lines in the fins followed by fin clamping to the body and sitting on the bottom of your pond and a few will start to isolate themselves and upon examination have an excessive amount of slime. I’ve actually smelled the ammonia around koi tanks and smaller ponds with overloading of koi and poorly maintained water quality.
So what’s a koi hobbyist to do? What’s one of my favorite sayings? “The solution to pollution is dilution” but this time it comes with a serious caution. You don’t want to change the temp or especially the pH that will result in the remaining ammonia becoming MORE toxic to your koi because your water change raised the pH resulting in higher levels of ammonia toxicity – but water changes are the number one treatment. Other important considerations: Temporarily reduce feeding schedule like stop feeding for a week or two – reduce fish load – reduce your pond water turnover time – increase your biofilter capacity – and a little salt might assist the koi in dealing with the ammonia issue. In worse case situations you may want to consider pH management (with chemicals) in the downward mode and chemicals to bind the remaining ammonia – but this stuff gets me to thinking a temporary holding tank to save the koi, while you correct the problems identified with the pond.
I hopefully have covered most of the major points and given you some food for thought as to why ammonia is such an important issue for koi in the closed system of our koi ponds. A web search will provide a wealth of information on the subject and most koi books have something to say about the subject. If my crazy analogy between ammonia in a koi pond and human diabetes makes a little more sense now then my job here is done LOL.
"Koi" Jack Chapman