Fish die for any of a countless number of reasons. Fish kills happen somewhere every day. Yes, it is difficult to pinpoint the exact cause of a fish kill without having real time, first hand and immediate knowledge of any and all variables that could have possibly come into play. Some of these variables include the number, size and species of the fish, the size of the pond and population size of the fish, water temperature changes, rainfall, terrestrial herbicide/fertilizer applications that could have been washed into the pond during a rain, pool water overflowing from a rain event and washing the chlorinated water into the pond, aquatic herbicide/algaecide applications, etc.
Our last visit on November 8th included an EPA tested/approved algaecide and lake dye application. However, the applications were within the specified, labeled dosage rates for the products based on the water surface area that was treated. The products are non-toxic and EPA tested/approved for aquatic applications. Fish kills resulting from aquatic vegetation/algae treatments occur from oxygen depletions from the decaying vegetation and will occur within 5 days.
We understand fish kills can be frustrating - as part of our industry, we see them regularly as they occur in our area year round. Again, there are many factors that come into play. Because we were not on site at the time of the fish dying to determine the causing factors, it is difficult to give you an exact reason or cause. This time of year, the most typical cause we see is quick temperature swings and cool rain in warmer water.
This past weekend, this is what we saw area wide – Thursday/Friday brought cooler air temperatures that brought in cool rains into a pond with warmer water temperatures, which also causes oxygen swings. The fish we removed earlier this week were all forage type fish (primarily shad); unfortunately, these smaller fish - especially shad, minnows, reddear, etc. - are the most susceptible fish to any environmental changes.
I would like to be able to say, “Terry – this is what did it” with certainty. Unfortunately, taking all possible environmental variables and other non-environmental variables into consideration, it is extremely difficult to derive an absolute cause. But from our experience, the most likely contributing factor is the abrupt weather shift.
If you should have questions, or need additional information, feel free to contact me.
