Fish Out of Water

NB. The best treatment for any venom is antivenom.

Hot water is in fact an effective initial treatment for spined fish venom (and only spined fish venom). Although no-one knows why, and proper testing is impossible (because no-one is risking painful death to test a home remedy). As with all penetrating stings, the spine/sting must be removed as soon as possible. The closer the sting is to the heart, the worse the outcome, and the smaller window of time to get treatment. So time is of the essence and stopping to boil the kettle is going to use too much of it.

The affected limb should be submerged in 45°C water, for 30 minutes; while seeking emergency medical treatment. There is an antivenom available, and the patient will also need a lot of pain killers and close monitoring in a hospital. And probably a tetanus shot.

While hot water is effective as initial treatment, for stonefish venom, just pouring hot water over the stings does nothing. Submersion in 45°C water, for 30 mins is necessary, followed by the antivenom if possible, and large amounts of painkillers. As well as the excruciating pain, breathing difficulties, heart damage and nerve damage, stonefish spines can also cause infection and gangrene severe enough to require surgery. Just pulling out the spines and giving the area a warm wash will have little to no effect.

References Star Trek II: The Wrath of Khan (1982)