The Python is a really convenient tool for cleaning aquariums and doing water changes. However, the end is exposed, and this means that sometimes overly curious fish can get sucked (as happened to me recently when my large 6 inch goldfish got sucked in, causing a pretty scary few seconds as we rushed to cut off the suction).

This cover slips right on top of the python. I've created this with about a 6mm gap. The customizer also allows you to change the gap size.