MISSING FISH>>>>HELP

[nla81]

Hi all.
After fishless cycling for 4 weeks i had a water sample tested at my LFS. On getting the all clear i brought 6 zebra danios. Its now one week on and after returning home from work today one fish is missing. Ive tested the water for pH, Nitrate, Nitrite and Ammonia and all results seem to be ok, also there are no signs of the missing fish. Could the others have eaten it any ideas ???

 

[Robert]

what size is your gravel, and what type of plants or ornaments do you have, and what kind of filterdo you have??