I bought 4 clown loaches last week and immediately loved them. I did a water change about 5 days after I got them and like an idiot used only cold water to refill. The clown loaches went into shock from the drastic temperature change and never came out of it. The next morning they were all dead on the bottom. While I had seen fish go into shock from cold water, I have never seen one die from it. Lesson learned.