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Guppy deaths.


0216, South Africa

Posted Apr 01, 2015

To my everlasting discredit, I managed to kill at least 3000 of my beautiful guppys over the last ten days or so. I am usually very finicky about the quality of the water in my tanks but for some reason, I have of late not been as vigilant as I should have been.

It might be easy to blame the amount of work I do, or anything else for that matter, but the fact remains that I allowed a sudden, and lethal ammonia spike to kill at least 50% of my fish. Now the reason I keep guppies is that they are among the hardiest of all fresh water fish, and they will readily adapt to a wide range of conditions, but what I had lost sight of is the fact that guppys are among the first fish to die if ammonia levels suddenly spike. What is infinitely worse though, is that the evidence of an ammonia spike was right under my nose, so to speak, since I had been aware of a "swampy" smell in the fish room for at least a week, but somehow I did not connect the smell to an increase in ammonia in the tanks.

However, the sight of hundreds of dead fish brought the awful truth home to me in the most shocking manner possible. There is no "cure" for ammonia poisoning, apart from changing at least fifty percent of the water (and removal of the dead fish of course), to dilute the poison. Nonetheless, changing the water is one thing but to find a temporary home for several thousand fish is less easy, so there was nothing for it but to siphon off the water while at the same time replenishing the water at the opposite ends of the tanks. This of course may remove the poison, but the sudden change in water chemistry is just as dangerous, since a sudden change in pH and other parameters could raise their already high stress levels to the point where latent diseases might break out.

Nevertheless, the absolute certainty of losing more fish to ammonia poisoning far outweighed the mere possibility of something else happening, so I continued the process of replacing the water till I had replaced the entire water volume at least four or five times, but there remained the matter of cleaning out filters, and washing gravel and decorations- all of which drastically diminishes the nitrifying bacterial colonies that live there, but there was nothing to be done about that- it had to be done, and some colonies that were more than ten years old will probably take as long as that to recover.

In the meantime, the ammonia that had accumulated in the fish's tissues could not be removed so easily, so to counteract this, I added large amounts of non-iodated salt to the water. I always use salt in my tanks to control a lot of things, but the amounts I added now were huge. So there was nothing for it but to replace the water again after a day or so, to see what the results were, but my fish kept on dying, albeit at lower rates every day.

It is now 12 days since the tragedy occured, and no more fish have died during the last 24 hours. In total, I have lost about half of my guppies, but I will never again skip a weekly partial water change, no matter how busy I am. The cause of this tragedy is directly related to my failure to perform water changes for four weeks running, but this will never happen again. I have now installed garden sprinkler timers to pumps in the tanks to run for an hour every week to remove some water, and plastic toilet valve mechanisms to control the water levels during the pumping process.

Nevertheless, the reduced bacterial populations in my filters now demand that I check the water quality twice a day, where once every two or three days was the norm. It will in all likelihood take up to a year or more for the filters to re-establish themselves, but until I am sure the nitrifying cycle is fully functional again, I will be keeping a very, very close watch on the ammonia levels in my guppy tanks.

Don't let this happen to you- and don't wait until you can smell the ammonia, keep your water healthy, and spare your fish the agony of suffocating.

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