Mystery - Can Tetra Or Guppies Eat Zebra Danios?

[Freebird]

Need some urgent advise. Does tetras or guppies eat zebra danios?
 I have a 20G tank with 4 neon tetras, 2 black phantom tetras, 5 guppies and today i put 4 pink zebra danios (after quarantine for a week). After placing them in the tank i watched them for 2 hours and my observation was : 3 danios made a group and was swimming all over the place, exploring and one of them, loner was floating on the top. I thought that one will not make it. I went out for 5 hours and when i came back, to my horror one danio was missing. No trace of it at all in the tank. Just disappeared (the loner is still alive though). Can someone please let me know if guppies or tetra will kill a fish and eat it... and that too so neatly that not even a trace left behind.I did some research on google and found that danios can be a threat to guppies not vice versa.
Any suggestions..

 

[techen]

Most fish will eat dead fish, I'd check the substrate it's not been stuffed in there.

 

[hensonc4098]

They wouldn't kill and eat one, but they'd have no qualms in eating one that's dying/dead.
I wouldn't be surprised if the stress from being moved has killed one and then they've eaten it.
 
Pretty much all the fish that have died in my tanks have just gone missing. Nature recycles itself.