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Fresh Fish

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How fresh is that fish?

A newly caught fish is far fresher than any fish you'll ever buy in a shop. In fact, a freshly caught trout or salmon will have a shelf life of about 9 days at 0° C.

But what does this mean in real life? Can we really keep it in the fridge and eat it a week later? The answer, sadly, is no. Let's take a look at the details.

There are really only two issues that affect the storage life of a fish. The level of quality we want and the temperature at which it is stored.
  1. The quality of a fish, i.e. it's taste, smell, texture, looks etc, is at it's best at the moment of capture. After that it's downhill all the way. It's been shown in tests that the shelf life for a fish to be deemed 'High quality' is about half that of the normal shelf life that only ensures a fish will be of 'Acceptable Quality'.

  2. The higher the temperature is, the faster a fish will deteriorate (see the table below):


    TemperatureRate Vs 0° C
     0° C1x
     4° C2x
    10° C4x
    15° C6x
    20° C9x
    25° C12x

So, for example, at a typical fridge temperature of 4° C the shelf life of the fish would be half that at 0° C.

Note: When we're determining the freshness of a fish, we have to take into account all the various storage conditions that the fish has been subject to.


Let's look at an example

You've caught a nice trout at mid-day on a warm day. How fresh it will be when you eat it ?

Let's make the following assumptions:
  1. The fish was caught around mid-day and kept for 6 hours in a bass bag at 15° C

  2. The drive home took 1 hour with the fish in the boot of the car at 20° C

  3. Once home, the fish is quickly cleaned and stored in the fridge for eating the following evening (or frozen but allowing 1 day to defrost in the fridge)

How fresh will the fish be?
  • 6 hours at 15° C is equivalent to 36 hours at 0° C (6 x 6 hours)
  • 1 Hour at 20° C is equivalent to 9 hours at 0° C (9 x 1 hour)
  • 24 hours at 4° C is equivalent to 48 hours at 0° C (2 x 24 hours)

The total equivalent time is 93 hours, less than 4 days, at 0° C. This is less than the 5 day high quality shelf life, so the fish should be of high quality.


How long will a fish stay fresh on the bank or in the boat?

Let's redo the calculation to see how long a fish can be kept on the bank and keep it's quality.

We'll use the same assumptions:
  1. The drive home took 1 hour with the fish in the boot of the car at 20° C

  2. Once home, the fish is quickly cleaned and stored in the fridge for eating the folowing evening (or frozen but allowing 1 day to defrost in the fridge)

and as we've established
  • 1 Hour at 20° C is equivalent to 9 hours at 0° C (9 x 1 hour)
  • 24 hours at 4° C is equivalent to 48 hours at 0° C (2 x 24 hours)

Which means that out of our 5 day shelf life, 57 hours (about 2.5 days) has been used up, leaving us the equivalent of 63 hours to keep the fish on the bank. The table below shows us how long this is in real life:


Temperature63 hours @ 0° C
 0° C63 hours
 4° C32 hours
10° C16 Hours
15° C10 Hours
20° C7 Hours
25° C5 Hours


A bass bag can make all the difference

As you can see from the table above. On a warm summers day at 25° C you only have 5 hours on the bank (or in the boat) before you reach where the stage where the quality of the fish is likely to deteriorate to being 'acceptable' rather than 'high'.

The good news though is that a proper bass bag can keep your fish at around 15° C and will double the time you can keep a fish on the bank to 10 hours before deterioration is likely to become a problem.

This why we recommend every trout fisherman to use a good quality bass bag.

Click here to see the range of bass bags we carry for trout and salmon.