When I was raising nigripes fry, the most deaths of larvae, as well as metamorphed fish, was when I moved them or tried cleaning the tank. They didn't take kindly to it. Got scared to death. I figured if I ever tried them again, they would only be moved once, into a small reef tank that could handle all the overfeeding. Lots of sand and rocks. Hope Cujo pulls through. Keep us posted.
Dan
Dan