Over 2 weeks all our 20 yo stock dying one or two each day. All show signs of suffocation, nothing else. We have a well established 7cu m pond with many streams, waterfalls and plants.
we live in a remote region in Egypt, with no vet facilities nor services. We have our own test kit to check water. Recently we introduced few “fan tail” koi to the stock, (they were quarantined for almost a year in another pond). Some say they stressed the old stock and caused them to die, but not convinced with such reasoning. All been removed, but fish still dying. Today last remaining fish gonne ,out of 40! I need to make sure nothing wrong with the pond before introducing new fish. Knowing the reason can help future prevention...
Thank you