I have my 10 gallon divided, the water level about 2.5 inches lower than the top of the divider... My 2.5 year old Spartan, on one side and Maine, my younger guy on the other. Maine finished his job as a dad, from the spawn tank so I put him in there. They were fine, no breaching the walls, nothing. Today, getting ready for work, I look in the tank and both are minding their own business on their own sides, then I pick something up, look back, and MAIN IS ON SPARTAN'S SIDE!!!!
Poor Spartan was trying to avoid the confrontation! I didn't have a net at a quick reach and I wasn't about to rummage for one while my two males were face to face! So I used my hand and divided them, herding Maine back to his side by lifting the divider... Luckily no one got hurt, or even nipped.
My hand was still in there after I fixed the divider back to it's spot, and Spartan comes along and nestles himself in my hand (nyawwww). He's definitely my little boy
I'd feel bad for leaving him in that tank with Maine... So I moved Maine to my extra 3 gallon tank, not taking chances.