If you have a fully cycled filter that is working on your tank, I would not change it. To prevent fish being sucked up by the filter you can place a sponge filter over the intake. Just cut a slit in the center of the filter sponge and slip the inlet tube down into it. It keeps fry from being sucked up and gives an extra layer of biological filtration.
Filter sponge laying on my desk top
Sponge in place on filter tube
The extra sponge is easy to clean using the gravel vac during a water change. Things stick to the outside but otherwise it stays pretty clean by itself.