There are probably more aquatic species in the world than there is anything of anything (microbes excluded). About 250 000 of these species are currently known to us, though estimates suggest there may be eight times as many in existence. Projections made in the 2010s concluded that 91 percent of marine organisms had yet to be described. Naturally, only a handful of this diversity of beings are fish, crustaceans, fish-like organisms or even algae; those fit for human consumption are fewer still. Even with these caveats, a cookery book – albeit one with a taxonomic touch – must involve some triage. In deciding which fish to feature, we have looked to balance the familiar and the curious; to mix the universal and the local, the wild and the farmed, the saltwater and the freshwater; and – as befits an international organization with nearly 200 Members – to paddle far and wide, leaving no main region uncovered. Of course, not all species will be available in all places. In fact, no single place on earth is likely to feature the range of fish featured here: we’re well aware that our pursuit of diversity will run into practical availability concerns. Further, in some cases, what can be sustainably obtained in one region might not be so elsewhere. This is why we have often suggested replacements – not only for fish, but also for accompanying vegetables and other ingredients – in the hope that readers will be inspired to think up equivalents themselves. In the kitchen, to coin an ad hoc phrase, substitution is the mother of empowerment.

Over stretches of time that most of us readers and writers of cookery books the Amazon has shuffled and reshuffled its surrounding landscape, forming lakes where water once flowed and causing myriad river creatures to branch off genetically.

From the extravagant Tyrian purple pigment, secreted by the Murex snail, to the Judaic ban on fish devoid of fins and scales; from the glamour of pearls, the oyster’s response to alien intrusions, to the vulgar co-option of mussels and clams as a proxy for female genitals;