I got up this morning to find the bigger of my 2 oscars had died during the night. There were no signs of illness, and I checked the water with my API this morning..water parameters were very good. I did a 25% wc yesterday, but did the same wc on all my babies so I can't see how that had anything to do with it...the one that is left is absolutely heartbroken! I hate it when I lose one of my babies like this! The only thing I can think of is I had a friend put some feeder goldfish in with them while I was out of town 4 days ago...I wonder if they were carrying some infection?? If I had just been here, I could have told her that while I do feed them the feeder goldfish as a treat every once in a while, I always qt them in a 10 gallon for 4 weeks first! I have made many mistakes over the years, but even as a newbie I could see that those feeders weren't the healthiest...I am so sorry I wasn't here baby!