The 1st shot is right focused on the head, but, with shallow DOF I assume, so, the rear part of the body is out of focus. That's a nice pose of the bichir. The focus is on the middle of the snakehead body, (near the pect. fin), and again with shallow DOF, the head area looks a bit out of focus. I suggest you use aperture priority mode and set aperture in smaller size (larger aperture number), also set ISO higher (if without using flash light).