When the summer months come along, we always get at least a few calls or emails that go something like this. "I think I killed all my fish", or "I lost all my fish overnight!".
Something like this is hard to experience but it can be something we learn from too. Fish loss, especially significant fish losses in a pond are usually caused by rapid oxygen depletion. The dissolved oxygen level drops so low, that the fish simply can't survive. Another situation that is less common but still impactful involves the temperature of the water. Oxygen levels can be very good, but if a pond heats up too much, it can cause stress and death, despite the dissolved oxygen being fine.
I put a series of three (short) videos together this week that talk about the various reasons fish may be lost in mass. Hopefully with some of this information ahead of time, you can avoid experiencing any kind of fish kills in the future.