I agree in most cases.
This breed of FW crayfish never gets bigger than 3 inches and is quite passive, only comes out to forage for scraps and shys away from Tetras.
He's the biggest predator in the tank. I cause him more stress than any resident in the tank, and the only thing I really do to him is try to offer him food with my fingers.
Alrighty.. I don't mean to be preachy. I personally
would keep them in a species only tank.
I've seen people keep ACF with turtles then come on forums going 'derp how come my frog is missing a leg?'.
This forum section just started no horror stories yet please! lol..
Anyways I guess you answered your own question, your frog hides when the lights go out (I honestly suspect he is not a fan of a certain armored and clawed predatory crustacean). These frogs are only successful at catching live fish at night when they catch the fish resting. They are strictly ambush predators, I've seen them chase fish -- it's generally close but no cigar and they give up after a bit.
In the wild, ACF feed mostly on arthropods and carrion, they are generally not 'fish eaters' outside of home aquaria.