I have a 28" ck and he does very well with the rays. He was raised with rays his whole life.
Other fish is a different story. He is the king of whatever tank he is in, dosnt take any crap from anyone, and isnt afraid to take very big bites out of anyone who gets in his way.
I have one to.
About 21inches.
He stays by himself most if the time. I've got a clay pot that he hides behind. I think thats important.
But when you throw food in there, look out. He feeds right besides my rays.
Problem is, every fish is different.
I got lucky.
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I have a BGK about 8-9" with my hystrix group. He was fine for a few months but noticed as the rays got near his tube he lives in, he'd shoot out and kinda bite at the rays. Since then I've raised his tube up off the bottom about 6", suspended in the water column. No more aggression ever now he's moved to the penthouse.
Feeds fantastic with the Rays and actively will go beneath them to steel the odd massivore pellet without any fear. I think a knife is a great tank mate with rays
I had a 12" BGK in with my big rays for almost 6 months then one morning it disappeared. So I went round 2 bought one at 3" now it's almost at 12" and it's in my pup tank with no issues, feeds with the rays fine and does the same thing previous post stated will go under there disc to steal food.
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