I'm trying to check whitebait temperature after cooked and it always seems to be a lower temperature than expected e.g. even after boiling the fish, removing the fish and adding the thermometer, the thermometer can show 40-50c.

I'm currently using this thermometer, however, although it goes in the fish(seemingl fully), perhaps as the fish is so small air is getting to it and so an accurate read isnt been given.

  1. Is my current thermometer inappropriate and are there any specific thermometers which can be used specifically to check small fish such as whitebait. I imagine the needle has to be very small considering the fish size and most thermometers i find are not much different than the one I linked.

  2. Is it possible that the fish reaches the safe temperature e.g. 62c however as soon as I remove the fish from the water it rapidly cools so by the time the thermometer goes in the fish tempertaure already decreases to say 40c? If yes how is it best to check fish temperature? I know you can look for texture and opaquness of of fish however I'm not good at judging with my eye so I'd rather use something more objective like a thermometer.
  • 2
    What happens if you stick just the tips of the probes into hot water? Do you get a reasonable temperature or does it seem to be "averaging" in the air? Sometimes cheaper thermometers aren't just sensitive right at the tip of the probes, so they'll work okay on bigger things where the whole probe is in the food, but not for small things.
    – Cascabel
    Apr 9, 2017 at 14:55
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    The thermometer is likely to cool the fish signficantly when you put it in. Remember the thermometer is (presumably room temperature) metal. Any heat in the fish will be conducted in to the thermometer before it can measure the temperature accurately. I would suggested heating the thermometer in hot water before inserting it into the fish.
    – canardgras
    Apr 10, 2017 at 9:17

1 Answer 1


Whitebaits are thin. If you are putting them into hot water or hot oil, it should take under a minute for the whole fish to reach the temperature of the surrounding liquid, assuming they are no thicker than 5mm. Heat transfer at this scale is rapid. If you have frozen whitebaits of course, that would take much more time. My suggestion is to cook them once thawed.

It is not practical to probe the inside temperature of such small fish. Your thermometer, unless faulty, should be well capable of measuring the temperature of your cooking water. You would have to design an elaborate experiment to get at the core temperature of the cooked fish. Unless you are after the data rather than wanting the fish cooked, don't bother.

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