How to tell if fish is fresh

August 5, 2026 · Seafood 101 · MERO 18

Learning how to tell if fish is fresh isn't about luck or gut feeling — it's a short series of checks you make with your eyes, your nose and your fingertips, in under a minute. At a cold bar like ours, that inspection happens every single day before the ice ever touches the first plate. Here's the whole routine, exactly the way we run it, so the next time you're standing at a seafood counter you'll know precisely what to look for.

Freshness is decided before the kitchen ever opens

No cook, however talented, can rescue fish that showed up tired. That's why at MERO 18 — the seafood restaurant tucked inside Mezcal Boutique Hotel, in the heart of downtown Cancún — the first "cooking" of the day happens at the scale and the receiving table. The box arrives, it gets opened, smelled, handled. Anything that doesn't pass the inspection never reaches the cold bar. It's that simple, and that non-negotiable.

The good news for you is that the same signals a seafood buyer checks are in plain sight for anyone. You don't need to be an expert — you just need to know where to look. Let's break it down.

The checklist for how to tell if fish is fresh

A whole fish tells its story in five places. Check them in this order and you'll have your answer before you ever ask the price.

1. The eyes

It's the first thing we look at. A fresh fish has a clear, bright, slightly bulging eye — as if it were still alive. As freshness fades, the eye sinks, clouds over and takes on a grey, milky film. Dull and sunken? Walk away.

2. The gills

Lift the gill cover if you're allowed. It should be a deep, wet, clean red — the color of living blood. When a fish has been sitting for days, the gills fade toward brown, dull pink or grey and turn slimy. It's one of the most honest tells there is, precisely because it's so hard to fake.

3. The smell

Here's the myth worth killing: fresh fish does not smell "fishy." It smells like clean ocean — like the tide, like salt water with a mineral edge. That sharp, sour, "fish market" odor we all know is actually the smell of freshness leaving the building. If it stings your nose or hints at ammonia, don't eat it.

4. The firmness

Press the flesh with a finger. On a fresh fish the flesh is firm and springy: it dents and bounces right back, leaving no mark. If your finger leaves a crater that lingers, the muscle has already begun to break down. On a fillet, look for tight, moist-but-not-slimy flesh with the flakes still holding together.

5. The shine and the scales

Fresh fish skin gleams, coated in a thin, clear (not cloudy) film and holding vivid color. The scales sit tight and well attached; if they shed at the lightest touch, that's a bad sign. A dull, dry or faded look gives away the passing days.

Oysters, clams and conch: proof they're still alive

Shellfish come with one extra golden rule: they must arrive alive. A fresh oyster or clam keeps its shell shut, or snaps shut when you tap it. If a shell is already gaping and doesn't react, it's discarded without a second thought. They should feel heavy, full of seawater, and smell of exactly that — the coast. This is why, at the bar, oysters are shucked to order, right in front of you, and never before: an oyster that's been open for hours has already lost what made it special. It's the reason we serve them by the piece — natural, ponzu, shaved, or dressed in aguachile — and never in advance.

What to demand at any seafood spot

The checklist works at the counter, but once you're seated the room gives away just as much. Here's what we wouldn't mind you demanding of us:

• The raw product should be on display, over plenty of clean ice — not hidden away in the kitchen.
• The menu should change: a place that respects the sea works with the catch of the day and says so, instead of promising the same twenty species year-round.
• It should smell clean when you walk in. A fresh seafood spot smells of ocean and lime, never of old fish.
• There should be turnover: a steady flow of people means the product isn't aging in the case.
• They should welcome your questions. A good server knows what came in today and where from, and enjoys telling you.

And if you're wondering whether eating raw seafood is safe at all, the short answer is yes — when the place respects the cold chain and daily turnover. We unpack it calmly, without scaremongering or impossible promises, in is seafood safe to eat in Cancún?

The final test is on the plate

All the theory gets settled in the first bite. Fresh fish has a clean, firm texture, a subtle sweetness and a short, briny finish — never that strange, lingering, metallic note that stale product leaves behind. In a catch-of-the-day ceviche, where the lime barely grazes the fish, there's nowhere to hide: if something wasn't spotless, you'll notice instantly. That's exactly why cold-bar dishes — ceviches, tiraditos, aguachiles, oysters shucked to order — are, on top of being delicious, the toughest exam a seafood kitchen can sit.

Fresh, every day, on Avenida Nader

At MERO 18, freshness isn't a slogan — it's a routine that starts before we open. We work with product that comes in daily, a cold bar you can see, and oysters shucked in front of you. That consistency is part of why we hold a 5.0 rating with 145 reviews on TripAdvisor and rank #24 of 1,914 restaurants in Cancún, alongside a Travelers' Choice award. You'll find us at Calle Mero 18, corner of Av. Carlos Nader, downtown Cancún — a short walk from the ADO bus terminal and five minutes on foot from Parque de las Palapas, open to everyone: you don't need to be a hotel guest to grab a seat at the bar.

Come see for yourself

The best way to learn to recognize fresh fish is to eat a lot of it. You'll find us at Calle Mero 18, corner of Av. Carlos Nader, downtown Cancún — inside Mezcal Boutique Hotel, open every day from 7:00 am to 11:00 pm for breakfast, lunch and dinner. And if you want to understand where your food actually comes from, start with what "catch of the day" really means.