Who are you calling ugly? Don't judge a fish by its looks...

Pulling the innards out of some black-and-white, slippery, dodgy-looking character at 8.30am isn't something I make a habit of. But I'm now planning to do it more often. Courtesy of an early morning getting-down-and-dirty session at the Billingsgate Seafood School I've discovered that cuttlefish, the big ugly sister to squid, despite its alarmingly less-than-alluring looks, has much more flavour when treated with tender care and doesn't toughen up so quickly.

"Avoiding cuttlefish ink projectile vomit is the real knack," says C J Jackson, our teacher, who's on the Food Catch Advisory Committee and an avid proselytiser of cuttlefish and other under-loved – yet plentiful – non-endangered and wholly sustainable ugly fish as she demonstrated how to gently ease out the ink sac intact.

With a bit of knife dexterity I managed to do so (though one fellow participant ended up with viscous, sticky ink all down her cleavage) and smugly added it to my risotto nero to give it the all-important dramatic colour before adding finely sliced strips of the adroitly cleaned cuttlefish head – sautéed for 20 seconds each side, no more. It may look like something a Macbeth witch would concoct, yet even more unctuous and perfectly suited for our miserable summer was cuttlefish stew made with the leftover tentacles slow-cooked with red onion and Rioja.

Besides instructing adventurous home cooks in how to prepare more forbidding, neglected cuttlefish, spider crab, gurnard and more, Billingsgate Seafood School runs courses with Sustain for chefs keen to broaden their repertoires and, it has to be added in such impecunious times, improve their gross profit as, presently at least, these uglier fish are vastly more affordable. Cuttlefish seems currently to be leading the shoal in terms of culinary cool and creative versatility.

Dip a little deeper – a good many of these uglier fish do lurk at the bottom of the sea-bed – and it emerges that some of the UK's most glamorous restaurants are refreshingly not judging their fish offerings by their looks. Caprice Holdings, whose A-list restaurants such as The Ivy, J Sheekey and Scott's are actively encouraging their diners to put aside piscatorial snobbery and try different species to promote ocean conservation. Tim Hughes, the chef director, says: "I see it as our duty to impart our knowledge to a wider audience so everybody realises how important it is to cherish our fish stocks and safeguard our seas. We champion lesser-known species in plentiful and sustainable supply."

Often ugly, the surprise catch of the day from the day-boat Princess Louise (name-checked on the menu) has become a talking point at Butlers Wharf Chop House, one of D&D's flagship restaurants, by Tower Bridge. Chef Martin Kroon says: "Besides being ethical, our 'sea-to-plate' specials offer the opportunity for more interaction with diners, who are taking a keen interest in knowing more about what they are eating. We buy directly from Chris Bean, taking literally whatever he catches, which often includes red or tub gurnard, spider crab or scad. Chris fishes inshore from Helford River in South Cornwall and only discards fish that is undersized." Bean emails Kroon with his catch of the day, which leaves Cornwall at 5pm in an ice box and arrives by road courier at Chop House by 3pm next day, giving sufficient time to improvise how best to serve the latest delivery.

More blatant still is "Ugly Fish Friday", audaciously pioneered by Lusso, the Square Mile fine-dining arm of CH&Co caterers. "We wanted to make a voluble stand against the fishing-quota system that sees dead fish thrown back into the sea and show that such neglected fish have culinary value, too," Paul Hurren, the managing director, says. Their "high net worth" financial and legal clients may be used to choosing higher-status fish on restaurant menus, but are proving incredibly receptive to gurnard, megrim and dab cooked to order.

Buoyed by their success, Lusso held their first "Ugly Fish Friday" street-food pop-up at Whitecross Market last Friday to reach out to a wider city (and beyond) audience. Assisted by TV's The Fisherman's Apprentice Monty Halls and Nigel Legge, Lusso's chefs cooked dishes from fish landed 24 hours earlier, including spider crab and mackerel fish cakes with salsa and cuttlefish, wrasse and hake gumbo. Curious, rain-drenched customers queued down the street, making it an off-the-scales success and netting £450 for a fisherman's charity, too.

Follow twitter.com/uglyfishfriday for the next event

Dogfish/Wrass/Rig

Its name varies according to where it is caught, but doesn't do much to makeover its decidedly ugly countenance. Charlie Lakin, of Marquis of Alkham, says wrass "requires a little dressing up". He often has it on his lunch menu pan-fried with crushed potatoes, garden peas, sea astor and crisp, air-dried ham. Moshi Moshi use dogfish as a substitute for endangered eel in unagi teriyaki or deep-fried.

Gurnard

Gurnard, red, yellow or tub, has somewhat intimidating eyes, lives on the sea-bed and stirs up food with its "legs", narrow fins adapted for this purpose. It is quite bony and best purchased from the fishmonger with fin and skin removed. Avoid buying during its summer spawning season. At J Sheekey, gurnard is pan-fried with creamed sweetcorn and cured ham.

Spider crab

Prehistoric looking with alarmingly gangly legs, spider crab has a tougher spiky shell than brown crab so it's far more challenging to pick its meat. Simon Rogan, of L'Enclume, favours its chunkier and sweeter meat simply mixed with mayonnaise, lemon juice, soft herbs and a little cayenne pepper and spread on hot toast. "Buy only spider crabs that are less than 120mm wide," he says.

Stone bass

A substantial textured fish also known as wreck fish, as it is often found around sea wrecks, is gradually gathering culinary credibility bordering on fashionable status. Even ultra-sophisticated Scott's feature stone bass ceviche with chilli, coriander, lime and plantain crisps. Tom Kerridge, of Hand & Flowers in Marlow, gives stone-bass crispy-skin treatment in a warm salad.

Scad

Otherwise known as horse mackerel, an equally undesirable calling card, scad has black alien-like eyes plus a thorn in its tail that doesn't endear it to diners. But Martin Croon, of Butlers Wharf Chop House, says it has a pleasingly firm texture, good bite, is somewhat earthy and a little fatty and not entirely dissimilar to blue-fin tuna. It is a frequent arrival in his catch of the day.

Cuttlefish

At his new restaurant at Kensington's Baglioni Hotel last week, Moreno Cedroni created a dazzling dish of cuttlefish lasagne with a vivid parsley sauce, finished with diced susci (an Italian take on sashimi) of cuttlefish and a dramatic drizzle of cuttlefish ink.

Jean-Denis Le Bras, head chef of Michelin-starred Sketch, serves it as an appetiser briefly sautéed and chilled with diced red and green pepper, cucumber, courgettes, kaffir lime zest, sesame oil and toasted sesame seeds.

Alyn Williams, at The Westbury, prepares cuttlefish cut like tagliatelle, marinated with celery seeds and oil, cooked quickly on a grill, then combined with celery and radish.