Zoo News

Over the weekend of January 6th, the Zoo suffered a large fish die-off in Gibbon Lake. As the lake is managed as a natural system subject to the elements, isolated deaths do occur on occasion. However, the keeper staff noted several fish that appeared to be having issues over the weekend. The aquatics staff quickly collected samples to test the water quality in-house. Water samples were also collected to send out for specialized testing at outside laboratories. It soon became clear that only fish were affected as turtles in the lake had no issues. Any fish that were found deceased were pulled from the lake. The staff veterinarian performed post mortem examinations on those fish and collected tissue samples to help find a cause. These samples also have been sent out for testing to help determine exactly what happened. Right now a definitive cause has not been established. However, there are some causes that have been ruled out. The most common cause for fish die-offs is oxygen depletion. When our aquatics staff tested the water in-house, oxygen levels were more than adequate. In addition, the recent cold temperatures normally help maintain oxygen levels. Another common cause for a die-off is infection or parasites. This cause has not been completely ruled out. However, the veterinarian did not see any obvious signs of infection or parasites on post mortem examination of the fish.

Beginning Friday, January 11, 2018, we will be dropping the level of the Gibbon Lake to locate and perform repairs to a leak in the lake that is unrelated to the fish die off. These repairs that could take several days. During the time that the lake water is lowered the lemurs and gibbons will remain inside and will not be visible to the public. The Zoo’s aquatics staff will monitor the lake during this process and relocate any fish that remain in the lake as water levels drop.