This is what I have done. I bought sponges made for especially by Fluval for Fluval intake strainers so Fluval filters won't kill your fish. Sadly, I only learned about them after 2 fish were killed. What I would would like Fluval to do is include these sponges in the box with the filter or suggest that they be bought separately. I don't know why they don't do this. As the store owner told me, "fish get sucked up and killed all the time" by these Fluval filters. Very sorry to hear your friend's guppies. It is heart breaking; peppered corys are adorable with unique personalities. My family and I had grown as attached to them as we would our dog or a cat (and expected to have them for 10-15 years). So, when folks laugh it off or say, "Chalk it up to experience," and so forth it kind of hurts. In my opinion, it's negligent on the part of Fluval. I just can't understand why they don't put a warning somewhere or just put the sponges in the box and charge an extra $6.99 which is what I paid for each of them. Thanks for backing up my experience my fish loving friend ( :