I'm glad your knife is thriving. I have a ABK and he NEVER comes out of hiding. I actually thought he was dead (and probably eaten) for a long time. Cause no matter how I moved the decor around I couldn't get him to appear. But one day I see him swimming around again....? But only for a few seconds. Then back in his log.
Well, the light probably startled him. As you probably know, fish(except for sharks) have no eyelids. Try letting in only a little bit of light in at a time before turning on the aquarium light
The BGK died 2 months ago from my angelfish... but thank you!
By Angelfish? Angelfish doesn't harm bgk at all. They don't see them as threat or territorial issues with them. I have mine with three big Angles. But yes u can't trust behavior of fish. Anyways sad to know.