1. Use a sponge pre-filter. A sponge pre-filter is a piece of foam that fits over the filter intake. It helps to block small objects, such as fish, from being sucked into the filter.
2. Choose a filter with a small mesh size. The mesh size of a filter is the size of the holes in the filter. A smaller mesh size will help to prevent small fish from being sucked into the filter.
3. Place the filter intake away from areas where fish like to swim. Small fish are more likely to be sucked into the filter if they are swimming near the intake. Try to place the filter intake near the back of the tank, where fish are less likely to swim.
4. Monitor your fish regularly. Keep an eye on your fish to make sure they are not getting stuck in the filter. If you see a fish that is stuck, turn off the filter immediately and carefully remove the fish from the filter.
By following these tips, you can help to prevent your small fish from getting stuck in the filter.