Coral is an animal, not a plant, and coral welfare in both aquarium and wild settings raises legitimate questions as they respond to environmental stress.
Coral welfare is at the most uncertain end of animal welfare science. Corals have simple nervous systems without centralized processing, and evidence for pain experience is weak. However, they are definitively animals that respond to environmental stressors including temperature, chemistry, and light changes. Their bleaching response - expelling the symbiotic algae that give them color and energy - is a stress response with significant welfare implications for the coral animals themselves. Aquarium coral welfare primarily involves maintaining appropriate temperature, chemistry, and light conditions that prevent chronic stress responses. Conservation-motivated coral propagation in aquariums provides an additional welfare-relevant benefit.