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Deep-fried Horse Mackerel (Aji Fry)
Prep Time
20 mins
Cook Time
6 mins
Total Time
26 mins

Deep-fried Horse Mackerel (Aji Fry) is a traditional Japanese home-cooking dish. Butterflied horse mackerel is coated in breadcrumbs and deep-fried to a perfect golden colour.

The method of butterflying the fish is unique as it opens the fish from the dorsal side instead of the belly side. This method is called ‘sebiraki’ in Japanese and the very detailed instruction for butterflying a fish is included in this recipe.

Don't forget to see the section 'MEAL IDEAS' below the recipe card! It gives you a list of dishes that I have already posted and this recipe that can make up a complete meal. I hope it is of help to you.

Recipe Type: Main
Cuisine: Japanese
Keyword: crumbed fish recipes, deep-fried fish, fried fish
Serves: 2
Author: Yumiko
Ingredients (tbsp=15ml, cup=250ml)
  • 4 horse mackerels (whole, medium size, note 1)
  • ¼ tsp salt
  • ¼ tsp pepper
  • tbsp flour
  • 1 egg beaten
  • cup panko breadcrumbs
  • Oil for deep-frying
  • Shredded lettuce
  • Tonkatsu sauce (or other sauce such as Worcestershire sauce, note 2)
Butterflying Fish (Sebiraki method, note 3)
  1. Remove the scales on both sides of the fish by sliding the tip of the knife from the tail end towards the head.

  2. Place the knife where the tail begins, facing the blade to the head. Move the knife at a very low angle towards the head and trim the bony scales (scutes) along the lateral line, which ends close to half-way.

  3. Remove the head by cutting at a slight angle behind the gill and the front fin.
  4. Using a finger or a narrow knife, remove the guts from the opening, without breaking the thin flesh around the belly.
  5. Rinse the fish and clean the cavity in the belly. Pat dry, including inside the cavity.

  6. Starting from the head of the fish, make a shallow incision on the dorsal side all the way to the tail. The incision needs to be on your side of the back bones.
  7. Using the tip of the knife, extend the incision towards the belly along the backbones. It is easier if you lift the flesh that is already removed from the bones so that you can see where your knife is cutting.

  8. Detach the rib cage by cutting the rib bones along the back bones.

  9. Continue to remove the flesh along the back bones until you reach to the belly, but keep the belly skin intact. You now have a butterflied fish with the bone in.

  10. Flip the butterflied fish over (skin side up) and make an incision on the other side of the dorsal in the same way.
  11. Chop the backbone at the tail end, keeping the tail attached to the flesh (note 4).

  12. Now you have a butterflied fish fillet. If small pieces of guts are left on the belly, wipe them off using kitchen paper.

  13. Place the tip of the knife where the rib bones start and trim the flesh with the rib bones very thinly. Do the same on the other side of the rib bones.
  14. There is a very sharp hard thorn in front of the anal fin. You need to remove it. I used kitchen scissors for this.
  15. The last step is to remove the pin bones from the fillet. Run your finger along where the backbone was and feel the bones to locate them. Remove all of them using a pair of fish bone tweezers or pliers.

Frying and Serving
  1. Sprinkle salt and pepper over both sides of butterflied fish fillets.
  2. Working one fillet at a time, coat a fillet with flour, then pat to shake off excess flour. Place it in the egg and coat all over. Allow excess egg to drip, then transfer to the breadcrumbs.

  3. Cover the entire fish with breadcrumbs, and gently press down so that a good layer of breadcrumbs is stuck on both sides. Repeat for the rest of the fillets.
  4. Heat oil in a frying pan to 170°C / 338°F. The oil should be about 3cm / 1¼” deep.
  5. Gently place the crumbed fish skin side up. Do not crowd the oil with too many fish pieces (note 5). Cook for about 1-1½ minutes, then turn the fish over. Cook for further 1 minutes or so, until golden brown (note 6).

  6. Transfer the fried fish to a tray lined with kitchen paper to drain excess oil.

  7. Place two Aji Fry pieces with shredded lettuce on each serving plate. Serve immediately with the sauce of your choice.

Recipe Notes

1. Also called yellowtail and jack mackerel in Australia.

My fish was 20-22cm / around 8¼” from head to tail (120-140g / 4.2-4.9oz). The size of the fish can be smaller or larger. But for ease of handling, I don’t recommend using too small or too large fish.

2. I used Bull-Dog Tonkatsu sauce as the thick fruity sauce goes well with the crumbed fish. By mixing Worcestershire sauce and tomato ketchup, you can make a similar sauce.

You can of course use Worcestershire sauce or other sauces.

3. You will need a very sharp knife for this. Please also see the video in the post, which shows how to butterfly a fish using the sebiraki method (opening from the dorsal side).

Step-by-step photo of how to fillet horse mackerel in the sebiraki method.

If you find it too hard to make a butterflied fish, you can cut two fillets out of each fish instead. The appearance is not quite the same as the traditional Aji Fry, but it’s still delicious.

4. Do not discard the back bones with flesh on them. You can make crunchy Fish Bone Senbei out of them. Please see the last section in the post for how to make it.

5. I fried two fillets at a time.

6. If your fish is smaller/larger, the frying time needs to be slightly shorter/longer respectively.

7. Aji Fry can be frozen for up to 1 month. It is best to freeze them before deep-frying. Thaw in the fridge overnight, then deep-fry.

8. Nutrition per serving. It is assumed that the oil absorption rate is 20% of the weight of the fish fillet.

serving: 280g calories: 847kcal fat: 46g (71%) saturated fat: 6.7g (34%) trans fat: 0.2g polyunsaturated fat: 9.7g monounsaturated fat: 26g cholesterol: 159mg (53%) sodium: 749mg (31%) potassium: 772mg (22%) carbohydrates: 63g (21%) dietary fibre: 3.9g (16%) sugar: 5.1g protein: 43g vitamin a: 5% vitamin c: 4.7% calcium: 15% iron: 35%