I’m obsessed with fish that clean other fish: they remember their clients, much like a hairdresser

I'm campaigning for legal protection for cleaner fish, because no one has done a proper assessment of the impact of removing them from Scottish reefs

I was in my 50s when I first became aware that cleaner fish existed, when I met a fisher who sold them to Scottish salmon farms. Each year, around the world, such farms use more than 60 million cleaner fish to eat - or clean" - parasites off other fish. But the natural habitat of the cleaner fish is the reef.

On a reef, each cleaner fish has clients that visit them to have their parasites removed - sometimes much bigger fish or predators such as sharks and rays. I was intrigued to discover the cleaner fish would gently massage these clients with their fins and make sure they were comfortable.