Seafood cookery can get even the most confident of cooks' nerves jangling. The thought of gutting and filleting, overcooking or undercooking a beautiful fillet is off-putting if we're lacking confidence. It’s a shame, given that most of what's required is relatively straightforward once you’ve practiced the techniques (you can find our vast selection of fish cookery guides here) and well worth the effort. Fish's freshness is another area ripe for uncertainty – we’re used to the telltale signs that meat and vegetables are past their best, but when it comes to fish, we're sure a few of you have wondered, well, isn’t it meant to smell a bit fishy? (The answer is, in short, no.) 

The first and most important rule is to make sure you’re buying your seafood from a reputable fishmonger. But we know there are times you might need to double check how fresh your fish is at home, particularly if your plans have been pushed back and you’re wondering whether that bream has been in the fridge a day or two too long. With that in mind, we've asked the pros for their top tips when it comes to fresh fish and seafood.

We'll dive in right at the very beginning; buying your fish. It goes without saying that heading to your local reputable fishmonger is a must – they'll not only be able to give you advice on what to buy and how to best cook it, but also point to signs of freshness and what to look out for when you take it home. When it comes to picking the right fishmonger, Brendan O'Sullivan, of Hackney's Fin and Flounder, says those who can tell you exactly where their fish has come from and when are usually worth trusting. Displays which are packed with plenty of ice (which keeps fish fresh for longer) and fair prices (we all love a bargain, but particularly cheap fish might be a cause for concern) are green flags, too, he adds.

Ideally, we'd only buy fresh fish the day we planned to cook it, says Rex Goldsmith, of The Chelsea Fishmonger – while it might not make us sick, fish doesn't stay at its peak for long, so planning your trip around your cooking plans is wise (he compares it to fresh bread; it's fantastic for a couple of days, but long after and it's only good for toast). However, Rex says there are things we can do at home to maximise its freshness. 'Work out which is the coldest part of your fridge,' he advises. 'If I was buying fish on Thursday for Saturday night, I'd put it in the salad crisper at the bottom. Also, plastic bags aren't good for anything apart from maybe getting your fish home dry – wrap it in paper instead. For shellfish, take them out of any wrapping, put them in a bowl and cover with a wet tea towel in the fridge.'

We know what you're thinking – that's all well and good, but what happens if I've already left it a day too long and I'm not sure whether to cook or toss? There are a few ways you can check if fish is still fresh at home, and we'll kick off with the most obvious. Despite what we might have heard, fresh fish shouldn't smell fishy – its aroma should be clean, slightly oceanic and similar to fresh water (it's sometimes described as being like cucumber). Earthy, ammonia or overtly fishy smells are all bad signs that suggest fish is past its best. Rex says: 'Fresh fish shouldn't really have a strong smell – it should have a nice clean, fresh smell of the sea. If there any strong, really unpleasant smells, you want to avoid that.'

Stuart Ralston, chef at Aizle, Noto, Tipo and the seafood-focused Lyla in Scotland, also recommends checking for any off-putting smells behind the gills specifically – fresh fish will only have a 'very faint ocean smell' there, he says.

If you've bought a whole fish, looking at the eyes can give you a clue as to whether it's at its best – the eyes of fresh fish will be clear, plump and shiny. Avoid fish where they are sunken and cloudy – in most cases, anyway. 'Fish should have beautiful, bright eyes,' agrees Brendan. 'Certain fish – black bream springs to mind – can have cloudy eyes when they come from the sea, but generally bright, shiny eyes are a really good indication of freshness.'

The skin and flesh are important areas to check – an easy test is to push a finger into the skin. It should spring back quickly – if it stays indented for a few seconds, that suggests the fish is past its best. The flesh of fresh fish should feel firm and sturdy as opposed to soft, while the scales should be well-connected to the skin. And while we probably don't need to tell you that you should steer clear from overly slimy fish, a little slime isn't a problem – Brendan says a shine shows fish has some of the 'goodness of the sea' and hasn't dried out. Stuart agrees: 'Checking the flesh is firm, not soft, with shiny skin also helps – it should have a little slime on it, this will show you it's fresh from the sea.'

When fish are fresh, their gills are bright red, and they slowly darken over time once they’ve been caught. A good rule to go by is the brighter the colour, the fresher the fish. They should, like the flesh, also feel clean, rather than slimy. Brendan says you can ask your fishmonger to show you a fish's gills before you buy. 'I love it when people do that,' he says, 'because we're proud of what we do. Fresh gills are the brightest blood red, but go from red to brown and then they can even be so washed out that they have a green colour.' 

Ultimately, buying fish the day you plan to cook it and always visiting a respected fishmonger means you'll rarely have to question whether seafood is fresh, but we know life happens – now you know the telltale signs, spotting on-the-turn fish will be a breeze. As Stuart says: 'If you have to keep smelling it and aren’t sure, then it’s probably no use – fresh fish is really easy to tell apart from bad.'

You're armed with tips and ready to master the art of seafood – our recipe collection is this way.