I rearranged my entire tank today in preparation for new plants. It brought up quite a bit of silt in the sand with all the replanting so I did 2 70% water changes.
Well, I siphoned my favorite guppy male. That is the only thing I can figure out because he is gone. I even tested by using some brine shrimp to draw them out and hoping he was just hiding.
I also really stressed out one of the females, but she seems okay now.
WOW...that's a lot of water to change out in one day. Except for a dire emergency, I never change more than 50% in one day. Smaller, more frequent water changes are better than one massive one. If the water gets cloudy from some too -energetic housecleaning, I just hook up an extra filter to the tank, maybe do another water change the following day if needed.
I still can't believe it happened. But, I won't use any syphon but the python from now on. I have a filter piece that goes on the end of it, keeps fish from being pulled in.
It might have jumped out maybe? check down near the back of the tank, I found one of mine there once, it was all dried up Always have the tops on my tank now.
I've done that too, sent a tiger barb in the bucket and poured the bucket in the toilet (which makes it flush automatically) watched him go down Try not to feel too bad, accidents happen
Well, I'm going to go over to my LFS and if not there to Petco and try and find a replacement. Not because I need one, but because I really liked him. Very young and a Green Cobra.
I know accidents happen, it's just that it had to be my favorite one.
That is the only thing I can figure out because he is gone. I even tested by using some brine shrimp to draw them out and hoping he was just hiding. 
.
But, I won't use any syphon but the python from now on. I have a filter piece that goes on the end of it, keeps fish from being pulled in.
Try not to feel too bad, accidents happen 
