‘I don’t know,’ I confess. I keep the camera out of his reach, but lean in to show him the photos. Our shoulders graze when he scoots closer to me for a better look. Neither of us move to keep them apart. Hugh stares intently at the camera screen.

‘What do you think? And be honest.’ I give him a serious look, and he returns my gaze with one just as serious. His eyes are a deeper blue. I make a mental note to stop thinking about how often they change colour.

‘I don’t know,’ he says hesitantly.

‘Are you just saying that because you don’t want me to find one?’

‘No, Millie, honest.’ He crosses his heart with his fingers in a gesture that reminds me of children. It’s so endearing that it softens the blow of his answer.

‘It’s not enough, is it?’

‘I’m afraid I don’t think so.’

A pit forms in my stomach.

‘We still have a lot more dives to go,’ he says, his voice soft and reassuring.

‘You shouldn’t be the one comforting me about this.’ I try to sound nonchalant, but my voice comes out flat and glum. ‘I bet you’re thrilled.’

‘No,’ Hugh corrects me. ‘Although I have to confess, I don’t know why you’re so hell-bent on finding this fish. You can prove corals can rebound another way. You can emphasise the pollution problem another way.’

‘I could, but people can identify with a fish; fish are less abstract than coral.’

Hugh nods thoughtfully. ‘OK, but coral bleaching is often one of the easiest ways to make people understand what a crisis global warming is because something literally changes colour. Take what happened in Florida, for example. One hot summer and boom, all the coral turned black – and died.’

‘But most people don’t even know that coral are animals. They don’t even know what dead versus bleached coral looks like! They don’t even know zooxanthellae!’

‘Millie, hardly anybody knows zooxanthellae. They can learn. And that’s beside the point.’

We’re seated so close. I feel more heat under the scrutiny of his gaze than I do from the blazing sun. ‘Why do you care so much whether or not this fish exists anyways?’ I ask.

‘Well.’ Hugh sighs and leans back. ‘Because I really don’t think it does. I think coral bleaching killed it, and I think it’s important to acknowledge that. We have to make people see that sometimes there is no coming back from the decisions we’ve made. We can’t turn back time.’

‘I think I’m going to prove you wrong.’

‘We can agree to disagree.’

‘Fine.’

‘Fine.’

I don’t want to keep thinking about the wrasse, so I change the subject. ‘If,’ I say, leaning back and closing my eyes against the bright sunlight, ‘you could have had anything for lunch, what would you have?’