Just once, and then only for about six months. I guess it's to entrenched in my psyche. I usually just scale back when I loose interest or get busy with something else for a while.
once, when I didn't fishkeep seriously, all I kept was 2 tanks with guppies and a betta. Dropped out from May '09 to November '09, when I got back in, I decided to keep more tanks and different types of fish, like cichlids and bichirs.
Dropped out not really ever. I've gone without having any fish (though I always kept at least a 55 cycled for that unforseen opportunity.) more than once. But never really dropped out I'm still on the forums everyday and always working my next diy project in my head.