I have 6 zebra danios that are cycling my 29 gallon tank. I went to vacum the gravel and I noticed one in the gravel. It was really tiny, then I looked around the bottom and saw alot more that were underneath and on top of the gravel. My question is how do i get them out without killing them and what do I feed them? They are about the width of a human hair and the length of 3-4 millimeters.