I have CRS and platy fry, not guppy fry. I was watching my tank thinking "gee I can't find many of my 10 shrimp or two of my fry" and then watched a shrimp get sucked up. In near tears I turned off the filer and looked inside and there were 8 shrimp and 2 fry still alive in my filter pad! Holy cow! I cut up a chunk of the filter pad and shoved it in the hole. My filter still works fine and no more missing friends. I'm basically telling you this story because I have to disagree that healthy fry won't get sucked up a filter and think its better safe than sorry on covering the hole. Good luck with your new babies!