Why Waiting to Cut Your Fish Matters

Posted on August 19, 2025 by Local Fish

When it comes to preparing high quality fish, especially for raw preparations like sashimi or crudo, timing is everything. One of the most overlooked steps is letting the fish rest on ice before filleting. This simple choice makes a big difference in texture, flavor, and shelf life.

What is Rigor Mortis? Why Does It Matter?

After harvest, fish enter a natural stiffening process called rigor mortis. During this phase:

  • Muscles contract
  • Tissue dehydrates
  • Texture becomes firm and rubbery

If you fillet during rigor, the result is often tough, dry, and less flavorful meat… even if the fish is otherwise exceptionally fresh.

The Food and Agriculture Organization notes that fish pass through pre-rigor, rigor, and post-rigor phases over the course of hours to several days, depending on species and storage temperature. Cutting during rigor leads to lower tenderness and reduced shelf life.

Ideal Resting Time: 24 to 48 Hours on Ice

Resting a fish whole (gilled and gutted) on ice allows the flesh to relax as rigor mortis resolves. This typically happens around 24 to 36 hours post-harvest, though timing varies with species, water temperature, and handling.

At this point, the fish becomes:

  • More tender
  • Easier to fillet cleanly, maximizing yield
  • More flavorful as natural umami compounds develop

For yellowtail (Seriola species) — a favorite for sashimi — the sweet spot is 24 to 48 hours on ice at 32 to 36°F (0 to 2°C).

A study in Fisheries Science found that yellowtail stored at 0°C showed significantly better texture and moisture retention when filleted after rigor mortis resolved (roughly 24–36 hours postmortem) (Saito et al., 2015).

Wild fish show similar benefits. Morison et al. (2004) documented that postmortem shrinkage and muscle tightening in wild species can last from 12 hours to as long as 7 days, depending on species and conditions. Resting on ice helps minimize these effects, improving fillet quality and yield.

Why Stress and Handling Matter

Resting time isn’t the only factor — how fish are handled before and after harvest changes quality as well.

  • Stress speeds rigor: Roth et al. (2006) found that stressed Atlantic salmon reached full rigor in just 2–4 hours, while rested salmon took 12–36 hours.
  • Rest restores balance: Daskalova et al. (2019) showed that fish handled gently and allowed to rest entered rigor later (12–21 hours) and began resolution around 32 hours, resulting in better water-holding capacity and texture.
  • Post-rigor filleting boosts yield: Le et al. (2019) reported that catfish filleted after rigor had higher yield, less contraction, and reduced drip loss compared to fish filleted earlier.

For wild fisheries, this reinforces the value of quick bleeding, icing, and careful handling: practices fishermen (especially those in the Local Fish Project network already know are essential to quality.

How to Tell When Rigor Mortis Has Resolved

Practical signs you can rely on:

  • Flexibility: The fish bends easily at the tail or mid-section without resistance.
  • Body Shape: In rigor, fish are stiff and curved. Post-rigor, they relax and straighten.
  • Texture on Touch: During rigor, the flesh feels tight and tense. Post-rigor feels softer and yielding.
  • Time + Temperature: At 32 to 36°F (0 to 2°C), many species resolve rigor in 24–36 hours, though some wild fish may take longer.

Quick Tips for Best Results

  • Bleed, gill, and gut immediately after harvest
  • Store on ice or in an ice slurry at 32°F
  • Do not fillet the same day unless cooking right away
  • For sashimi/raw use: rest 24 to 48 hours
  • For cooked dishes: 12 to 24 hours is usually sufficient

Bottom line: Resting your fish isn’t lost time, it’s an investment in quality. Whether it’s a yellowtail destined for sashimi or a wild-caught rockfish for the grill, giving the fish time to move through rigor mortis ensures better flavor, tenderness, and yield.

References

Daskalova, A., Ribarova, F., Stefanova, R., & Denev, P. (2019). Effect of pre-slaughter stress on rigor mortis and flesh quality in fish. Aquaculture International, 27(3), 773–783. https://doi.org/10.1007/s40071-019-0230-0

Food and Agriculture Organization of the United Nations. (1999). The storage and handling of fresh fish. FAO Fisheries Technical Paper No. 331. Retrieved from https://www.fao.org/4/x5914e/x5914e01.htm

Le, T. T., Dang, T. T., Tran, T. N., Nguyen, T. V., & Tran, T. T. (2019). Filleting at different rigor stages affects yield, contraction, and drip loss in Tra catfish (Pangasius hypophthalmus). Foods, 8(2), 69. https://doi.org/10.3390/foods8020069

Morison, J., Johnston, I. A., & Macleod, M. (2004). Post-mortem shrinkage of four species of temperate and tropical marine fishes without freezing or preservation. Fisheries Science, 70(2), 325–331. https://doi.org/10.1111/j.1444-2906.2003.00798.x

Roth, B., Moeller, D., Veland, J. O., Imsland, A., & Slinde, E. (2006). The effect of pre- or post-mortem muscle activity in Atlantic salmon (Salmo salar) on rigor mortis and the physical properties of flesh. Aquaculture, 257(1–4), 504–510. https://doi.org/10.1016/j.aquaculture.2006.03.020

Saito, T., Watanabe, Y., & Ando, M. (2015). Postmortem changes in the muscle of farmed yellowtail (Seriola quinqueradiata) at different temperatures. Fisheries Science, 81(1), 123–131. https://doi.org/10.1007/s12562-014-0823-4

Why Waiting to Cut Your Fish Matters