Ya I know they can get really big. I researched it before.
And also bought one fish only coz they emit electrical signals for finding food. Keeping two in a medium space meant sure shot fighting among the two. This aquarium also has 2 caves. One big hollow tree trunk and a glass tube. Also this is just a grow out tank. BGK are a little bit of slow growers. Mine has grown around 2.5 inch in 6-7 months. But they do grow large. Once it grows a little bit bigger, I will transfer them to a 55g.