Hello everyone, I am stumped? my koi are not eating much they are sluggish looking at foot and are hiding in the plants , no predators have been around my pond has a net over it all water testing is fine, no algae issues, only 7 fish in a 4500 gal pond,40 inches deep in center, a month ago we has a heat wave and nor it has cooled off a bit but still 80 in the day upper 50s at night but it has been this way for 10 days, I have a skimmer , a filter , a bottom drain, a pump to push water from side to side, they were fine all spring and early summer, the just hang under the plants all day, I have a lot of plants and was wondering if there is to many plants?, any ideas would help, thank you