I have lost a few fish, and I do mean lost. They just disapear with out a trace, as a matter of fact I am missing one right now. I have checked all the filters, plants, and such and he is mia... and no chance of jumping ship there is only one strip 1/4" x 6" for a HOB filter, and a 1" x 1" square for feeding. Now that said it is possible that if he is dead he may be stuck somewhere and you do not see him, I have had that happen.