Fish Hook, London W4

These days, a fish restaurant that really is a fish restaurant is a rare bird indeed. Most seafood restaurants are so nervous of alienating carnivores that they end up with as much meat on their menus as a steakhouse.

It takes a certain resolve to stick it out as a specialist, especially if you lack the resources of a hotel or chain, so I admire the courage and commitment of Michael Nadra, chef and proprietor of Fish Hook in Chiswick, who recently opened on the site of what was an even more specialised South African fish restaurant called Fish Hoek.

Of the 14 dishes listed tonight, only one is meat (slow-roast pork belly) and two are vegetarian. The rest of the menu is swimming with fish and seafood, from prestige speciales de Claire oysters with champagne vinaigrette to monkfish wrapped in prosciutto, line-caught sea bass with root vegetable fondue and roasted organic salmon with steamed Shetland mussels.

As at Fish Hoek, most of these are available as either small or large servings. Cooking influences are just as flexible, reflecting the chef's experience in Petrus, La Trompette and The Ebury, running from classic French to modern Med, with the odd Asian reference popping up here and there.

Nadra has given the place a new coat of creamy beach-house paint and hung a series of handsome monochrome screenprints of fishy bits and pieces. Wooden-backed banquettes run down either side of the restaurant; and votive candles flicker on small, bare-breasted wooden tables. It feels just like a cosy seaside cottage washed up off Chiswick High Road.

A pretty dish of ceviche (£8.50) is a surprise, made up of three strips of marinated fish (tuna, swordfish and salmon) with a bobbly border of finely diced scallop. Everything is bright, lean, clean and fresh-tasting, and the scallops are particularly sweet and pure, given punch and definition by little glowing orange pearls of salmon caviar.

A second starter of three big Saudi king prawns served on a mound of garlicky risotto threaded with wild rocket (£8) would have been a better dish without the prawns. When they're this tasteless and overcooked, they merely get in the way of the respectable, easy-going risotto.

I'm not sure about this starter-or-main concept. In practice, it seems to mean miniaturising the main courses, cutting them down to size rather than rethinking them. Some of the resulting dishes look like those on Masterchef Goes Large. By that, I mean a talented home cook's idea of a cheffy presentation.

The majority of diners are thirty- and fortysomethings with the easy familiarity of regulars, discussing the school syllabus and planning seaside summer holidays in France. They don't seem to share my reservations, and neither John Torode nor Gregg Wallace turn up to stick a fork in anything, so don't take any notice of me.

In truth, my seafood ragu main course (£17) feels a bit like a maximised starter, coming as a rough-and-tumble of lightly seared scallops (aagh, cut in half), funny little penny-shaped baby-squid bodies, discs of Jerusalem artichoke and thumb-sized octopuses - what the Italians call moscardini - that is bound together with a thin film of herby, tomatoey sauce. It is pleasant enough, although it would need to be stewier and saucier if it's going to call itself a ragu.

Mahi mahi, also known as dorado and dolphin fish, is a solid, firm-fleshed fish from the Pacific. Here, Nadra has capitalised on its meatiness by combining a sautéed fillet with chorizo sauces, discs of waxy ratte potatoes and a clump of squeaky green beans (£15). Flavours are rustic and earthy, if a bit oily, demanding the elegant power of a Domaine Vaudoisey-Creuseford Volnay (£32).

Side dishes are a mixed blessing. A generous bowl of roast salsify with Alsace bacon (£3.50) is gutsy, but cooked with too much oil; and a Secrett's Farm mixed-leaf salad (£3.50) is uncharacteristically mean, so small it is gone in three forkfuls.

A little note on the menu that says "please allow 20 minutes for dessert" suggests someone cares enough to cook to order rather than turn out the usual array of done-ahead parfaits, sorbets and mousses. This would explain the fresh, crisp, scorchy nature of an individual apple tarte tatin (£5.50), the sugars and appley juices mingling with the pastry during baking to caramelise into crunch. It's so good I share it only at gunpoint, and seriously consider waiting another 20 minutes for a second one.

Fish Hook is a different sort fish restaurant to the nearby Fishworks with its on-site fishmonger. It's more of an honest and likeable neighbourhood joint that just happens to have chosen to cook fish. It would be good to see more whole fish and not just fillets, and less imported seafood, but the prices are fair, floor staff are friendly, and the cooking is well-intentioned. If I were a Chiswickian, I would consider it a fine place to spend an evening planning all the fruits de mer platters and whole grilled sea bass I'd eat on my summer holidays.

13/20

Scores 1-9 stay home and cook 10-11 needs help 12 OK 13 pleasant enough 14 good 15 very good 16 capable of greatness 17 special, can't wait to go back 18 highly honourable 19 unique and memorable 20 as good as it gets

Fish Hook, 6-8 Elliott Road, London W4, tel: 020 8742 0766

Lunch and dinner served Tuesday to Sunday; around £95 for two, including wine and service

Second helpings: Fish restaurants from head to tail

Fishworks 10 Church Street, Christchurch, tel: 01202 487 000 Mitchell Tonks' mighty chain of fish restaurants-cum-fishmongers is now eight strong. None of them have any meat on the menu - just great fish, house-made taramasalata, Italian fisherman's stew and fruits de mer platters.

Fishy Fishy Café Guardwell, Kinsale, County Cork, tel: 00 353 21 477 4453 As you would expect from a cosy lunch café in a picturesque port, Fishy Fishy specialises in locally caught fresh fish. There is a token meat dish (chicken salad), but everyone's too busy eating steamed mussels and grilled monkfish to notice.

Zilli Fish 36-40 Brewer Street, London W1, tel: 020 7734 8649 This somewhat retro Soho stalwart is the flagship of Aldo Zilli's Italianate restaurant collection. There may be steak on the menu, but why do that when you can have lobster spaghetti, tuna carpaccio or chargrilled swordfish?