Metropolis and Gotham City are not too different from New York, so…

Analytics, most likely

Are you sure it’s not just covered in curry?

Don’t quote me on that, but as far as I understand it, the scientists needed a control group for some experiment in breeding one of those species of fish, so they paired it with a different species, so far removed evolutionarily that the scientists believed there’s 0% chance of hybridization. Like there’s 0% chance of getting a hybrid of a platypus and a polar bear, for example. But then, against all odds and expectations, these two species of fish have produced a hybrid.