My 7 year old daughter has a, I think, 60L tank, tonight we came home to 5 dead fish, 1 Sissortail, 2 Harlequins, 1 Endler Guppy & 1 female guppy, who we thought was pregnant, we also lost another "pregnant" guppy earlier in the week, we just put in live plants, as we got told to put in the...