Sometimes, the best meals come from the simplest ingredients. Baked Fish with Tomato and Onion is a perfect example – a rustic, Mediterranean-style dish that’s both healthy and full of flavor. It’s the kind of recipe that feels elegant enough for a dinner party, yet easy enough for a quick weeknight meal.
At the heart of the dish is a fresh, mild white fish – something like cod, haddock, or sea bass works beautifully. Baking the fish allows it to stay moist and tender, gently absorbing the flavors of the ingredients surrounding it. Instead of heavy sauces or spices, this dish relies on the natural sweetness of onions and the bright acidity of tomatoes to bring everything to life.
As the fish bakes, the sliced onions soften and caramelize slightly, while the tomatoes break down just enough to create a rustic, savory sauce. A drizzle of olive oil, a sprinkle of salt and pepper, and a touch of garlic or fresh herbs like parsley or oregano round out the flavor. The result is a comforting dish that’s light, fresh, and deeply satisfying.
This baked fish is incredibly versatile. It can be served over rice, alongside roasted potatoes, or with a simple green salad. A squeeze of fresh lemon before serving enhances the natural brightness of the tomatoes and ties everything together beautifully.
What’s especially great about Baked Fish with Tomato and Onion is how effortless it is to prepare. It requires minimal prep and only one dish, making cleanup a breeze. Yet, the flavors are anything but basic – it’s one of those recipes that tastes like you spent hours in the kitchen.
Whether you’re cooking for family, hosting friends, or just treating yourself to a wholesome dinner, this dish is a go-to. It’s comfort food with a healthy twist – light, nourishing, and packed with Mediterranean charm.

Ingredients
- 4 fillets fish fillets
- 2 Tomatoes chopped
- 1 onion sliced
- 2 cloves garlic minced
- 2 tbsp olive oil
- 1 tbsp lemon juice
- 1 tsp dried oregano
- Salt and pepper to taste
Instructions
- Preheat the oven to 180°C (350°F).
- Place the fish fillets in a baking dish.
- In a bowl, mix together the chopped tomatoes, sliced onion, minced garlic, olive oil, lemon juice, dried oregano, salt, and pepper.
- Pour the tomato and onion mixture over the fish fillets and spread it evenly.
- Bake in the preheated oven for 25 minutes, or until the fish is cooked through and flakes easily with a fork.
- Serve the baked fish with tomato and onion sauce hot, garnished with fresh herbs if desired.
This recipe is so easy! I loved how the tomatoes made the fish super juicy. 5 stars!
Can I use frozen fish instead? Just wondering if that will mess it up.
Is it really that simple? I feel like I missed a secret step or something. Lol.
I thought the same thing too at first! But trust the recipe, it really is that easy. Just follow the steps and enjoy!
Didn’t turn out well for me. Fish was dry and the tomatoes didn’t help. Disappointed.
Sorry to hear that! Maybe it was overcooked? Fish can dry out pretty quick. I usually marinate mine before baking.
So delish! I added some chili flakes for extra kick and it was amazing. Definitely making again!
I didn’t have dried oregano so I used Italian seasoning and it still tasted good. Super easy recipe, no fuss.
This was delicious! The flavors blended so well! Will definitely make again.
Easy and pretty healthy. Mine needed like 30 minutes instead of 25, but the timing depends on how thick the fillets are. Still delicious.
Feel like I could make this with my eyes closed. So easy and simple!
This recipe is a game changer! The fish turned out so tender and flavorful. Can’t wait to make it again!
I loved the tomato and onion combo—smells amazing while baking. I served it with rice and it soaked up the juices perfectly.
Fish and tomatoes? Sounds weird but surprisingly good!
Fish with tomatoes? Sounds like a mess to me. Can’t imagine it tasting good.
I was skeptical too, but it’s really delicious! The tomatoes make it juicy!
Super easy and quick! Perfect for weekdays!
Not my thing. Fish should be grilled, not baked! 😒
I subbed lemon with lime, still tasted great! Cooking is all about experimentation! 🥙
Wow!!! The garlic with lemon is amazing. My family ate it all. 10/10
Haha love this! Garlic + lemon really makes it pop. Glad your family cleaned the pan 😄
Never thought to bake fish with tomatoes! Wow, so delicious!!
Easiest fish recipe! I added some cheese on top, delicious!
I thought it was okay, but my husband didn’t like it at all. He said too much onion.
This is such a simple and delicious recipe! My family loved it!
Tasty! But I forgot to add garlic and it was still alright.
I tried this but it didn’t turn out like the picture. My fish was dry, maybe I overcooked it?
It sounds like you might have cooked it a little too long. I usually check my fish at 20 minutes. Give it another try!
Easy weeknight meal. I doubled the sauce because I like extra, and honestly I could eat the sauce with bread all day.
Sounds nice but do i really have to preheat the oven? Seems too much work.
Preheating is important! It helps the fish cook evenly. Just take a few minutes to do it!
Honestly, I never preheat and it turns out fine. You could try skipping it 😁.
I don’t know much about cooking, but even I could make this! Thanks for the step-by-step!
I don’t know, it was kind of bland. I added some hot sauce, but still not my favorite. 😕
I tried this recipe but the fish was overcooked. Maybe I should’ve checked it sooner?
It’s easy to overcook fish if you’re not paying attention! Maybe next time set a timer for a few minutes before the cooking time is up to check if it’s done.
Easy to make. I added capers too. It was kinda salty but still good!
Too many ingredients for my simple taste, just needed salt n pepper.
This recipe is a game changer! So simple and delicious. My family loved it!
25 minutes felt a bit short for my thick fillets. I ended up baking 8-10 minutes more and then it was perfect.
The recipe’s fine, but I used chicken instead because fish is nasty 😝.
I don’t get it! Fish is delish! 🤷♂️
Chickens r great too, but fish has its own flavor. Anyway, glad u still liked it! 😁
It turned out a bit dry for me. Maybe reduce baking time by a few minutes?
I hate fish, but this actually tasted pretty nice! Who knew tomatoes could save it?
I dunno… I still think fish is gross. Tomatoes or not, it’s just fish.
Wow, that’s surprising! I never thought tomatoes could make fish taste good either. Maybe I’ll give it a shot now!
Tasty, but I feel like it lacked something. Maybe a chili or sumthin?
So easy to make! I made it for my family and they loved it.
I used salmon instead. Not sure if that’s right but it was good too!
Salmon sounds like a delicious alternative! Glad you enjoyed it.
The fish was good, but my kids wouldn’t eat it. They only like chicken.
This looks delicious! I love fish and can’t wait to try it! 😍
Yummy! Next time I might add some chili for a kick!
Made this tonight and it was super flavorful—tomato-onion-garlic combo tastes like it’s been simmering forever. The lemon really wakes it up. Will repeat!
Too much onion for my taste. But overall it was okay.
I’m not a fish person but this looked good? 🤔 Can I use tofu instead? What do y’all think?
Why do you need oregano? Fish tastes good with just salt. 🙄
But fish can be bland without some seasoning! You gotta try it with oregano, trust me.
I think oregano adds a nice flavor contrast! Salt is good, but herbs can really elevate the dish.
Fish? No thanks. Give me a burger any day!
To each their own! But I really think fish is healthier than a burger. You should give it a try!
This is just like my grandma used to make. Brings back memories! ❤️
I love that your grandma inspired you! This dish sounds delicious. Can’t wait to try it! ❤️
Looks easy, but my fish always turns out dry. Maybe my oven’s too hot or something? 🤔
Not bad, but I feel like it needs something extra—maybe a pinch of chili flakes or a caper/olive situation. Tomato sauce was good though. Also the instructions are kinda vague about covering the fish.
I think the instructions are fine? You just pour the sauce over the fillets… they’ll be covered enough. Also 25 min at 180°C seems right for most fillets—unless it’s super thick.
Agreed—tomato-onion is solid, but it could use a little punch. I’d totally add chili flakes and maybe some chopped olives for that briny vibe. The sauce already tastes good.
ehh, fish?? no thanks. idk why people like these dishes.
It was okay, but my fish kinda fell apart. Should I change the cooking time?
I used frozen fish fillets instead and it was still good! Thanks for the recipe!
Glad it worked out! I’ll have to try frozen next time. Thanks!
Frozen fish? That’s not the same! Fresh is always better!
Easy recipe! But I used chicken instead of fish. Worked out fine, my kids loved it! 😂
Sounds delicious! Chicken is a great substitute too. Glad your kids enjoyed it! 😄
This was so delicious! The flavor was amazing and the fish came out perfectly flaky. Will definitely make again!
I followed the recipe exactly, but the fish came out kinda dry. Maybe I baked it too long?
Why is everyone raving about this? It’s just fish and sauce. I honestly expected more.
I get what you’re saying, but sometimes simple is best! This dish is all about the flavors blending together. Not every meal has to be fancy to be good.
I mean, just fish and sauce? Sounds delicious to me! Plus, it’s healthy. Maybe try it before knocking it, yeah?
Yummy!
Can I use canned tomatoes instead of fresh? Just wondering.
I don’t know… the fish tasted kinda bland. Maybe I did somethin wrong?
Could you add cheese on top? I like melted cheese with fish.
Cheese with fish? That’s kinda weird. But hey, if you like it, try it out! Just don’t use too much! 😅
I think melted cheese might overpower the fish flavor, but whatever makes you happy! Cheese is awesome! 🧀
Baked fish with tomato? Who does that! 🍅 I quartered the tomatoes and used fresh herbs instead. Not bad.
easy to follow and cooks fast! My kids loved it. 🙂
180C feels too hot for fish. Mine got borderline tough on the edges. Maybe my oven runs hotter, but I don’t think 25 minutes is universal. Flavor was decent, just not the texture I wanted.
Not gonna lie, it was a bit bland for me. I’d add more lemon and maybe some chili flakes. Salt and pepper to taste should be taken seriously here.
Made this tonight—so simple and actually super flavorful. The tomato/onion mix cooked down nicely and the garlic wasn’t overpowering. I used cod and it flaked perfectly at 25 minutes. Will definitely make again!
That’s awesome! 25 minutes for cod is exactly what I’ve found too—nice when it flakes clean without drying out. Glad the garlic mellowed with the tomato/onion.
Delicious!
This was absolutely delicious! The flavors blended perfectly. Will make it again for sure!
This was a flop for me. My family didn’t like it at all. Disappointed! 1 star.
Fish with tomatoes and onions? Sounds healthy but I dunno… could be bland. I salted like the recipe said and it was still meh for me. Maybe I’m just picky. 😕
My garlic burned a bit even though I mixed it in with the sauce. I think 180°C is fine, but I’d rather mince it finer or reduce bake time by like 5 minutes.
Needs a little more seasoning. I added extra oregano and a pinch of chili flakes and it really woke up the sauce.
Not bad! I was worried the oven temp was too low, but it cooked through fine. Next time I’ll add a pinch of chili flakes for more kick.
I had the same worry about the 180°C—good to know it still comes out right. Chili flakes sounds like a great upgrade!
Next time add chili flakes but be careful cuz it can overpower the lemon. Also I think 25 min may be short if your fillets are thick—mine took longer.
Yummy 😋
I tried this but it turned out too dry. I think I overcooked the fish.
simple. tasty. I added a bit of chili for heat. Yum!
Pretty good, but mine came out a little dry. Next time I’ll check earlier than 25 minutes or drizzle a bit more olive oil. Still tasty and the oregano + lemon combo works well.
Dry fish is the worst 😅 But yeah, more olive oil / checking early makes sense. I’m trying this next time—oregano + lemon sounds like a winner.
Good point! I’ve noticed 25 min can be a little long depending on the thickness of the fillets. I usually start checking around 15–18 min and it stays juicy.
I don’t know about using fish with tomatoes. Seems like a weird combo to me.
I get where you’re coming from, but fish and tomatoes are actually a classic combo in many cuisines! Give it a try, you might be surprised.
Nah, that don’t sound right. Fish should be plain or with butter, not tomatoes! Sounds gross almost.
I don’t know… I made it, and it turned out super dry. Maybe my fish was old?
Kinda boring but still healthy. Like, it’s fine. Would use more lemon next time.
Kinda bland for me. I salt/peppered more than the recipe and it still felt like it needed more acid or herbs. Add basil maybe?
Not a fan of fish, but I tried it for my boyfriend and he loved it. I might even make it again! 😁
I followed it mostly, but I added a pinch of chili flakes because I like a little heat. Turned out great with crusty bread to soak up the sauce.
Fish? With tomatoes? Are we supposed to eat that?
Yes! Fish and tomatoes are actually a great combo. You should give it a try!
I tried it with frozen fish—didn’t bake evenly for me. Still edible, just not the same texture.
This is easier than I thought! Made it in just 30 mins. Will definitely share with my friends.
I mixed the recipe with chicken instead of fish. It was still okay! LOL.
Yum! Just made this for dinner, adding some capers next time! 🤤
Sounds delicious! Capers would add a nice tang! 😍
Not sure this is worth the effort. Just grill it next time.
I used cod and followed it exactly—great flavor, not too heavy. Will make again.
Can I use any fish? I only have salmon. What do ya think?
Too much oregano for my taste. I think I’ll stick with butter next time.
I actually love the oregano in this recipe! It adds such a great flavor. But hey, everyone has their own taste, right?
I followed it exactly but my fish turned out a little dry. Maybe my fillets were thicker? The flavor was still solid though.
Dry fish is the worst 😕. I’d try brushing a little olive oil on top before baking or covering it with foil for the first 15 minutes. Still, glad the flavor was solid!
That’s my guess too—thicker fillets can need a few extra minutes. I usually add 5–8 mins depending on thickness, and pull it when it flakes but still looks juicy.
Yeah, but how can you call this a recipe? Just throw some stuff together, lol.
I think it’s simple but tasty! Sometimes the easiest recipes are the best. 😊
Ain’t nobody got time for that! Why not just fry the fish, much quicker. 😒
But baking is healthier! Frying just adds all that grease. 😅
Come on, ya gotta try it! It’s about the flavor, not just the time. 😋
Fish fillets + tomatoes + onion = comfort. Simple but legit. My kid even ate it and she never eats fish lol.
That sounds seriously comforting—tomato-onion sauce on fish is such a win. Also love that your kid ate it 😂 I’m trying this tonight!
This recipe was amazing! The flavors are wonderful together.
I tried this and it was so dry! Maybe I cooked it too long?
I can’t wait to make this! Sounds delish!
This is giving “whatever you have in the fridge” vibes. Would’ve loved a bit more guidance on doneness (like internal temp). Still, it came out flaky.
I like the idea, but my tomatoes got mushy. Is that normal? 🤔
This was amazing! The flavors really popped. My family loved it!
Pretty good, but I think 25 minutes was a little short for my thick fillets. Next time I’ll check earlier and bake 5 more minutes if needed.
Good point—thicker fillets definitely need longer than a flat 25 minutes. I usually start checking around 20–22 and go by how easily it flakes, so “5 more minutes if needed” is spot on. Thanks for the tip!
I made this last night and it was gone in seconds! Will definitely make it again.
I don’t usually bake fish, but this was actually foolproof. 180°C for 25 minutes worked and it flakes beautifully. Will repeat.
Honestly I think 180°C is too hot for fish—mine dried out a little on the edges. Sauce was nice though. Maybe lower temp next try.
So easy! I made it for dinner and my kids actually ate the fish! Winning!
Not sure why, but my fish tasted kinda bland. Maybe I under-salted? The sauce was watery too.
Whoa, my oven runs too hot!! Burnt edges but still edible. Woot!
The ingredient list says 4 fillets fish fillets… like are we cooking the fillets or the fish fillets? 😅 Anyway, it tasted fine and the oregano is a good choice.
Made this tonight and it was surprisingly flavorful. The tomato-onion-garlic sauce soaked in really well—will definitely repeat.
Not bad, but the oregano was kinda strong for me. Next time I’ll use less and maybe add basil. Otherwise the fish stayed moist.
Totally get that—oregano can be pretty punchy. I’d try cutting it in half like you said, or even 1/2 tsp next time and adding fresh basil at the end.
The sauce turned watery in the dish for me, but the fish stayed moist. I think I should slice the tomatoes thinner or drain them a bit first.
I followed everything, but forgot the lemon juice. Still yummy tho!
Baked fish? More like BAKED FLAVOR! 🤤 This is a must-try!