African dwarf frog died?

We purchased four adf on Friday. This morning I wake up to one dead. I have noticed they aren't eating very much or not at all because I can't tell the differance between them. I followed all of petcos instructions. I have a filer ten gallon tank put water treatment in it. Waited 24 hours to put them in there. Not sure if it is because they were already sick or I'm doing something wrong. Please help me. Petco told us to fed them dried blood worms. They mostly just lay on the bottom