As well as the exclamation mark (a gasp of embarrassment about such a blindingly uninventive choice of name?) the restaurant comes with a credo. Fish is "the world's last great wild food resource", and the owners of Fish! are committed to buying the freshest possible, and knowing it has been caught most eco-friendly way. In the face of world fishing crises these good intentions may be a drop in the ocean, but such a responsible approach to running a restaurant is still a step in the right direction. Even so, the manifesto would be meaningless if the precious commodity for which seas have been plundered and wars fought were crucified in the cooking. Our meal reassured us it's not. For the most part, it's done with sensitivity and near-perfect simplicity.
The setting is a funky stainless-steel diner with the kitchen behind the counter. Overhead is a railway viaduct, which rumbles periodically - on one side Southwark Cathedral, on the other Borough wholesale fruit and vegetable market. Also in this Dickensian neighbourhood is a burgeoning number of specialist suppliers such as Neal's Yard Cheeses and the heavenly Konditor & Cook bakery. This makes it a food-lover's enclave during the day but eerily deserted at night, so the lights and movement in the restaurant appear like an exotic aquarium. With so little activity outside, my limping companion and I made our way painfully round the glass walls to the entrance on the Cathedral side, feeling more self-consciously exposed than the people indoors.
Whereas fish restaurants tend to fall into the cod-cockney fish-and-chip shop trap, or, aiming for gentility, swamp them in sauces that have you reaching for the fish knife in despair, this succeeds with a formula as simple as that of a steakhouse. We may be a generation of meat illiterates - who can tell their rump from their T-bone, ribeye from popeseye? Not I - but more of us can distinguish tuna, salmon and squid from each other than could our steak-eating predecessors. And at Fish!, by interfering with it as little as possible, we're encouraged to appreciate the difference between John Dory and sea bream, turbot and skate. The main attraction is the list of 20 species, of which only a third may be available on a particular day. Having chosen your fish of the day, it can be steamed or grilled, and served with salsa, hollandaise, herb butter, olive oil or red-wine fish gravy. The salsa was anonymous, but our choice of John Dory was inspired, grilled and served on lightly fried spinach and carrots which satisfied the need for vegetables without imposing themselves.
Devilled whitebait, lightly dusted with paprika, were crunchy without being battered, and a little bit fleshy. Their old associate from the Sixties, the prawn cocktail, has also been rehabilitated here to take its place alongside dressed crab, potted shrimp, smoked haddock with Welsh rarebit, and oysters at pounds 1 each. The fish soup, always a yardstick, was breathtakingly good. Not of the load-bearing consistency that keeps the croutons suspended on top, it had a silky lightness but as much fathomless depth of flavour as the thicker and richer variety. Croutons, rouille and cheese were already assembled on the side and, once in the soup, toppled in gently, adding saffron to the subtle chilli-hot spiciness of the broth.
Other fish-based stalwarts such as pie or cake are listed, along with less-appealing, fish-treated-as-meat sausage, tuna burger, swordfish club sandwich and tuna bolognaise. Though the spaghetti was fine, and the sauce convincingly bolognaisy, it can only be recommended to those who don't like the taste of fish. I do, and I kicked myself for not picking sea bass or scallops, cod or squid, which should have been as good as the John Dory.
Exemplary chips cost extra, as do bread and butter (the latter is portion- packed: if they're serious about sustainability it shouldn't be). With sensational renditions of sponge and custard, bread-and-butter pudding, and a bottle of wine, we were taken aback when the bill came to more than pounds 30 a head. But it was a slap-up fish supper. During the day, they sell fillets of fish and the sauces to take home - an even more uneconomical way of buying fish, even the best and freshest. Let them do the cooking and your money's well spent
Fish! Cathedral Street, Borough Market, London SE1 (0171-836 3236). Mon-Sat lunch and dinner. All cards.
More fish restaurants on page 46