I’ve heard the Thai expression of น้ำร้อนปลาเป็น น้ำเย็นปลาตาย “hot water fish survive, cold water fish die” before but of course it doesn’t mean literally that. In my second sister and dad’s case, cold water was the cause for their fish to die. My dad buried the 1 comet and 2 koi fish in his backyard today.
Back to the Thai saying above, it actually means it’s easier to catch flies with honey than with vinegar. As you can see that it has nothing to do with fish or cold water at all.