Tanksitting & porcupine died. Do I waterchange?

[Delphinus]

So, this sucks... I'm tanksitting for a fellow Canreefer, and unfortunately his puffer/porcupine perished sometime in the last 24 hours.

He was about 5" nose to tail, so reasonably small all things considered, and the tank is about 200g. None of the other inhabitants appeared stressed. But I'm concerned about the invisible cloud of death these things can release into the water.

Should I waterchange to be on the safe side? If so, how much?

The tank does have carbon but I don't know how old. Should I see about getting new carbon on as well?

Thanks for any thoughts/advice..