You’re not coming, are you? I thought I would be despondent if you didn’t come, but something must have changed for me because I’m not. Resigned, perhaps. Disappointed. But it is a small disappointment compared to so many others that it feels petty to dwell on it now.

There is good news, though – it seems my indigo hamlets have started mating. It is quite extraordinary, to be able to watch it. What a thing nature is. I noticed at about midnight – I was up, I couldn’t sleep, not after what had happened with the Asda man – and I was thinking about going to the rocks with my head torch but I decided to look in on the tanks instead, and thank heavens that I did! Honestly, I have seen photographs and documentaries but nothing prepares you for it, really, when you see it with your own eyes, close up, for the first time. It is exquisite.

Hypoplectrus indigo is their correct name, and I like it more than their common one. It makes them sound electric, doesn’t it? Electric, eccentric, hypnotic – they are all of those things, in a way. Their dorsal fin and frayed triangular tail are almost transparent, wispy and fragile, can you imagine? While the broad indigo bars running up and down their bodies are separated by thin white stripes, almost luminous in their lack of colour … The indigo is so deep, under my aquarium lights, that the white seems to glow, to carry the current that makes the hairs stand up on my arms as I watch them.

It is the synchronous nature of their hermaphroditism that is so unusual, you understand. Many species change from male to female at certain times in their life cycle, or develop in response to their surroundings, but to have both female and male sexual organs, to be able to simultaneously reproduce as both mother and father … to share so completely. Nature really is capable of so much more than us – I believe that now more than ever. When two indigos meet they form a mating clasp, a sort of spinning embrace that churns up the water so rapidly it forms a vortex. Three seconds it lasts, the vortex, that is all – but what a three seconds! They each take on a role, male and female, and release gametes into the vortex where they are fertilised. And then they swap. They join together in their mating clasp again and create a new vortex, except this time the former male acts as the female and the former female acts as the male. Do you see? They are both mother and father, and in being mother or father neither loses the ability to become instead father, or mother.

But I still can’t sleep.