I have 2 female bettas in a 5 gallon tank divided. The divider is clear mesh, so they can see each other, They have plenty of plants and hiding spaces, so they mostly keep to themselves but occasionally will "battle" through the mesh - it seems to keep them active and healthy.
This morning I came into my office to find both of them on the same side of the divider! No damage was done, but they are bettas and they were both pretty stressed out.
I moved one back to her side of the tank, and immediately checked the divider for gaps or holes. There are none, it is sealed tight from top to bottom and there are no holes (other than the tiny ones creating the mesh) in the divider that she could have slipped through.
I know bettas jump, but can their jumping be that precise, to actually jump OVER a divider? It comes up 1/2-1 inch above the water level. I've not seen either of them jump before, but it's an office tank so I'm only here during the day.