I made a rookie mistake the other day.. that has made me disappointed with myself. I bought some new food which I crushed into much smaller flakes as an alternative to the other fish food I have at the moment. I then stupidly decided to do a test feed to see if the fish would like it (I've had fish reject dry foods before). It seems this little guy loved it too much and ate as much as possible including hogging an algae wafer meant for my oto's a few hours before. I completely forgot the overfeeding rule, especially with fish this size. After half an hour had passed since I put the flakes in I only noticed 5 fish. This one had begun to swim upside down below the floating plants and was struggling to move. After a few hours, it was gone. So yes I killed my fish by overfeeding it.. Something I've not done in a very long time. It has really frustrated me that a fish died this way.