Is putting fake plants in there necessary and a tunnel?

[Aphone]

Or is just gravel ok?

 

[Brookster123]

There should be structure in the tank, it will keep the fish happy and less stressed.. Imagine yourself in a room with just a rug, no chair, no plants, no bookcase...no wifi

 

[venymae]

You can always find some rocks to stick in. Fish will stress in just a bare tank.