13 Simple Add-Ons That Upgrade Any Fish Sandwich

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Fish is a versatile protein that can be found in nearly endless preparations — fried, seared, baked, or grilled. And while it's usually served as a fillet along with side dishes or atop salads and pasta, it's especially delicious when made into a fish sandwich. From classic fried fish sandwiches to more inventive takes, like salmon gyros or shrimp sliders, fish sandwiches span cuisine types and tastes, making them a staple no matter your food preferences. 

Though the fish may be the star of the dish, it's important not to overlook the toppings that round out the flavors and textures of the sandwich. We asked three experts their opinion on what fish sandwich toppers take the top spots: Allie Hagerty, food blogger and recipe creator at Seasoned and Salted; Sally Cameron, chef and owner of A Food Centric Life; and Jim Foster, owner at Pelican Seafood Market & Grill in Ottawa, Canada. Read on to discover which simple add-ons they recommend to upgrade any fish sandwich.

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The most important thing when choosing a fish sandwich topping? "Don't mask the taste and texture of the delicious fish," explained Jim Foster. And the perfect condiment to complement (instead of overshadow)? Tartar sauce. "If I'm at my dad's fish market enjoying a haddock sandwich, it's tartar sauce all the way!" added Allie Hagerty. "The chunkier the better." 

This classic fish sandwich topping is usually composed of a combination of mayonnaise, lemon juice, capers, pickles, and a few herbs and spices. A simple tartar sauce is easy to whip up with ingredients you likely already have on hand at home, so it's not only tasty but convenient to add to your next fried fish meal. 

Even if you're a few ingredients short, don't worry — Foster has a nice shortcut. "We are big fans of really good mayo for creaminess and chopped dill pickles for acid balance," he told us — proving you don't even need capers and other add-ins to amp up your final dish. "The sour crunch is just what the sandwich wants," he explained.

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Coleslaw and fried fish are a match made in heaven — which is probably why this pairing has become so ubiquitous. The rich, savory taste of the fish and the crisp, refreshing bite of the coleslaw create a perfect contrast, resulting in a balanced, delicious bite.

"I think you need different textures, temperatures, and flavors [to enhance a fish sandwich]," said Allie Hagerty. "I love a hot, crispy piece of flaky fried fish paired with [...] a crunchy slaw, or maybe some simple arugula tossed with lemon for zip," she added.

Sally Cameron agreed, ranking "homemade slaw with fresh sliced cabbage" as one of her favorite toppings. While a traditional, mayo-based coleslaw never fails, you can also experiment with other flavor profiles to switch things up. Using a vinegar-based dressing instead adds a tangy, sour taste, or incorporating diced peppers (like jalapeños or chipotles) or hot sauce will give your sandwich some heat.

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Looking for the perfect blend of crunch, spice, and brightness for your fish sandwich? Look no further than jalapeños. These peppers have a spicy, grassy flavor and impressive crunch that cuts through the richness of fried fish or adds boldness to grilled or pan-seared fillets.

The pepper's earthy flavor and heat pair well with citrusy sauces, coleslaws, or sandwich spreads like mayo, cream, and aioli. If you prefer a milder heat, you can even pickle the jalapeños to take away some of the intensity — especially ideal for balancing fried fish sandwiches.

And the best part about jalapeños? Though they are often associated with Mexican food, they're a versatile pepper that spans across cuisine types. From Baja-style fish sandwiches to Southern-inspired alternatives, even just a few slices of jalapeño instantly elevate a simple sandwich. If you're cautious about spice, don't worry; you can remove the jalapeño seeds to dull the heat while still getting the signature flavor of the chili peppers.

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Aiolis are versatile sauces that can transform any sandwich — fish sandwiches included. While traditional homemade aioli is made with garlic, olive oil, and other ingredients (like egg yolks or mustard to help emulsify), there are countless variations with add-ins ranging from truffle oil to hot sauce.

Both Allie Hagerty and Sally Cameron recommended topping your fish sandwich with aioli to add flavor and creamy texture. "Homemade sauce is a game-changer in my book," said Hagerty. "A quick aioli with whatever you have on hand (fresh herbs, lemon, or chipotle-style) ... absolutely delicious!" Cameron recommended a similar combo: "A fresh lemony aioli, maybe with capers or herbs, is so good," she added.

Cameron also recommended creating a "cheater aioli" — spices or condiments mixed just with mayo. While not technically an aioli, adding ingredients like Dijon mustard, microplaned garlic, harissa, hot sauce, or smoked paprika — depending on what pairs well with your dish — to a creamy mayo base results in an almost-aioli sauce that tastes delicious (without much extra work).

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If you're looking for a topping that is fast and easy — but with a big flavor payoff — fresh herbs are the answer. Adding a few fragrant sprigs or leaves of your favorite can transform the taste of your fish sandwich with minimal time and effort.

"Italian parsley is my fave," said Jim Foster. The grassy, fresh notes of parsley are versatile enough to pair with most fish — so from blackened fish to classic fried fish sandwiches, the herb almost always fits the bill. Sally Cameron agreed that parsley was a great choice, along with a few others. "Soft herbs, Italian parsley, dill, and cilantro are nice," she added. 

Dill is a natural pair with salmon, and it is also often found alongside white fish like tilapia and cod. Along with the chef-recommended herbs, basil, chives, and mint are also commonly paired with different fish varieties, making them an obvious choice depending on the sandwich's flavor profile.

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Cheese and fish is a combo that some people tend to avoid, but there's one cheese that adds a creamy, salty complement to fish sandwiches: feta. "Whipped ricotta or whipped feta [is] cheesy but saucy too," explained Sally Cameron, so it pairs well with fish — unlike some other cheeses. "Really strong cheese will also overpower the fish, like a blue or Swiss," she added.

The feta-fish combo is fairly common in Mediterranean cuisine, with the whipped cheese being paired with everything from salmon to tinned fish like sardines. Making whipped feta is simple — just blend together the cheese, Greek yogurt, olive oil, and a dash of lemon zest in a blender or food processor. You can even mix in fresh herbs, like parsley or dill, or add other complementary ingredients like peas. The result is a smooth, luscious dip you can spread onto your bun to lend the perfect amount of creaminess to your final sandwich.

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Though bacon may seem more like a topping for burgers, it's a surprisingly delicious addition to fish sandwiches, too. "We make a panko-crusted haddock sandwich with bacon and cheese called the Moby Dick," said Jim Foster. "It's my favorite sandwich ever." 

The umami, salty flavor of the bacon pairs beautifully with the delicate, mild flavor of white fish, creating a bold contrast that will leave your mouth watering. Just be sure to choose a bacon cut that's well-suited for a sandwich to avoid overpowering the fish's flavor.

Build your sandwich similar to a BLT, adding toppings like bacon, fish, tomato, and lettuce — along with a smear of cool, creamy mayo — for something with familiar flavors. Or, if you want something more unexpected, consider fish blackened and coated in Cajun seasoning, cilantro-lime mayo, and crunchy bacon for a beautiful blend of acidity, salt, and fat that showcases the fish's natural flavor and texture.

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Tahini has a toasted, nutty flavor. And while it might not be the right condiment for every fish sandwich, when used right, it is absolutely delicious. Perfect for pairing with mild white fish like cod, halibut, or tilapia, tahini (or hummus) helps to enhance the fish's natural sweetness — without overpowering it. Tahini's bitterness, on the other hand, pairs well with the richness of fried fish. It helps cut through the fatty flavor to create balance, much in the same way a squeeze of lemon juice might.

But tahini doesn't just get points for flavor. It also has a versatile texture thanks to its silkiness and spreadability. It is thick without being heavy, offering unbeatable creaminess for sandwiches. Tahini also pairs beautifully with other Mediterranean spices like sumac, smoked paprika, or even chili oil, allowing you to play off of the flavors to create a well-rounded bite. Plus, it plays well with our other topping picks, like pickled onions or fresh herbs, for amazing versatility.

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Hot sauce is a condiment beloved by many. From eggs to burritos to pizza, people use this sauce to add heat to nearly anything, and fish sandwiches are no exception. Though it's not a traditional ingredient found on famed fish sandwiches like McDonald's Filet-O-Fish, it's still a delicious topping loved by many — including our experts.

Some hot sauces may be too spicy or too powerful for fish sandwiches, however, so it's important to thoughtfully choose the right recipe. Original Tabasco is usually a safe option, while Tabasco Family Reserve is a less prevalent variation from the famed hot sauce maker with a hint of malt vinegar, making it perfect for pairing with fried fish.

Alternatively, more adventurous options like green chili hot sauce or a spicy ponzu sauce introduce unexpected-yet-delicious flavors to the sandwich. Or, if you don't want to use the hot sauce straight, you can also dilute it into a spicy aioli made using mayonnaise, garlic, and lemon juice, so you still get some kick, albeit it a bit milder.

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Avocado's flavor may be subtle, but its impact on a fish sandwich is huge. The fatty fruit brings buttery contrast to a flaky seafood sandwich without overwhelming the flavor.

And while it tastes delicious, texture is where avocado really shines. You can slice it, smash it, or even whip it, and — no matter which preparation you choose — it gives a smooth silkiness to your sandwich. It's especially delicious when paired with the crunch of a fried sandwich, creating textural contrast that makes a dish memorable.

Avocado lends itself well to a certain flavor profile; cilantro, lime, cabbage, and salsa all taste wonderful with this ingredient. But just because those combos are most common, it doesn't mean you can't think outside the box. Consider adding avocado to your favorite mayo for an easy sauce, or keep it simple and top it with just a sprinkle of salt to really enhance its natural flavor.

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"Crispy fried shallots" — or any type of fried onion — add a rich crunch atop your sandwich, according to Sally Cameron. While fish and onions are a classic combination (often served caramelized over a fish fillet), you can take this same concept and translate it to a sandwich, too.

Though you can pre-buy fried onions at the grocery store, frying your own shallots is simple and adds extra flavor and freshness. Thinly slice the onions before dropping them into hot oil, stirring constantly to fry evenly. Once they're golden brown, remove them from the oil and lay them out on a paper towel-lined plate to soak up any excess grease. 

If you prefer, you can opt for another type of onion, though shallots have a more delicate, sweeter flavor that pairs well with milder fishes. For another unexpected twist, you can even coat the fish with crispy fried onions before pan-roasting for a unique take on combining these two ingredients.

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Pickled red onions can be found in recipes across cuisine types, from Greek to Mexican to Middle Eastern. They add a tangy bite to any dish, and these acidic veggies are especially delicious when paired with fried foods — like fried fish sandwiches — because they cut right through the richness. The crunchiness of pickled onions also contrasts well with the soft, flakiness of fish, giving the sandwich the perfect blend of textures.

"Quick pickled red onions, which I love to make and keep in the fridge at all times," are the perfect topper for a fish sandwich, said Sally Cameron. Luckily, they're also affordable, and it's easy to pickle onions at home, even for inexperienced cooks. Finely slice a red onion and make a simple marinade with sugar, vinegar, salt, and any herbs or spices you like. Add the onions, and in as little as a few hours, you'll have bright, crunchy pickled onions you can add atop any dish.