11 of the National Zoo’s stingrays and a few arowanas died this morning, according to the Zoo staff. The water in the Amazonia exhibit had reached a dangerous low oxygen level, and asphyxia is the likely, if not the confirmed, cause of death. The Zoo is adding oxygen meter readings to their schedule as well as water-quality tests.
The 55,000 gallon aquarium dates to the early 1990s, where it’s been home to a healthy and reproducing stingray population, which was sadly decimated by the decrease in oxygenation. Here’s hoping they’ll rebound well.