Luther not Hurler.Hurler (11"kel) is in a tank with a 3-4" geo. Luther has tried to eat him once. Grabbed his head but geo got away. I have added plants and the geo has a cave although he seldom uses it. I'm not sure if a dat will hide or if that's natural. The geo appears to have learned the game as he tries to hold still and all is well. Quick movement will interest the bass. Theo who is an 8" kel instigates much more as she will be the first to lunge at the geo. Theo wants to know what is going on all over the tank. Luther, not so much.
The geo actually will swim all areas of the tank with caution with the current set up. He has healed and eats all the time.
One thing I can tell you regarding my bass. You need to keep them well fed. They are used to a healthy large diet. If I skip feedings the geo is in much more danger.
This is just my experience with my kels.