Animals don’t have the same moral framework as humans, and their actions are often driven by instinct or curiosity rather than a concept of morality. If we can somehow prove that dolphins have a concept of morality and decide to act upon what they consider immoral, then I suppose that some could be considered malicious/evil. Given their cerebral volume, I believe dolphins have the cognitive capacity for this, but I’m not aware of research that proves it. If anyone has any scientific journals on the topic, that would be an informative read.

If they do in fact have a moral compass, that leans into a wider topic: absolute versus relative morality.