Hum I have a shubunkin lil guy (this springs batch) at my daughters in the 70 gal tank along with 5 other goldies (this springs batch also) who has gone nuts. He'll swim upside down spiral to the bottom swims funky and then chill on the bottom of the tank. Then he'll be just fine after a couple days. He's been doing this this past week 1/2 my son says. Any ideas as to why he would be doing this and not the others in the tank??? He's about 2" long and as my son says obese. I almost had my son "take care of him" but then he was acting normal again like the others...