Strange die off

[DrowningFish]

I live in Southern California and found these fish floating in my pond a few weeks ago. All of them were longer than 4 inches. Anything smaller is still alive and healthy. If anyone knows why this happened, please let me know so i can prevent it in the future. Thanks

 

[Yuki Rihwa]

Small fish live and big one died, my bet is that you have aeration problem in your pond...beware next heat wave coming up this week.

 

[Pharaoh]

+1

Generally big fish succumb to oxygen deprivation faster than smaller fish.

 

[DrowningFish]

Thanks guys. I have a waterfall and a spitter for the pond so I thought that wouldn't be an issue. I will definitely keep a closer eye on the temperature to prevent this from happening again.