Do corals which have bleached regrow the flesh and polyps that they have lost in captive reef aquariums?
It depends. If you are talking about a coral like acropora sp or other SPS, you can have bleaching without loss of tissue, and they will sometimes recover with the proper environment and nutritional support, though usually they cannot survive the stress of the expulsion of their zooxanthellae. If the coral has completely sloughed all its tissue down to a completely bare skeleton (like in a case of STN or RTN) it can be considered dead. If this is a coral like a euphyllia or other LPS, they can often survive severe tissue recession with the proper support and feeding.
More concerning is determining the reason why this occured.
It depends. If you are talking about a coral like acropora sp or other SPS, you can have bleaching without loss of tissue, and they will sometimes recover with the proper environment and nutritional support, though usually they cannot survive the stress of the expulsion of their zooxanthellae. If the coral has completely sloughed all its tissue down to a completely bare skeleton (like in a case of STN or RTN) it can be considered dead. If this is a coral like a euphyllia or other LPS, they can often survive severe tissue recession with the proper support and feeding.
More concerning is determining the reason why this occured.
References :