Fire crabs are most recognizable by their grey-green skin and the jeweled shell that they live in.The safety procedures are:

Wear properly fitted clothing - nothing loose

Have your wand in hand at all times

Wear dragon-hide protective gloves at all times

Never stand with the rear of a fire crab facing you

the fire crab is an endangered species that is currently protected. This is the case due to the fact that the fire crab shell is desired by both magical and Muggle people. The Muggles want the shell due to the wealth that can be obtained by removing the gems from the shell. Gems, no matter where you are from, have value, though some people will value gems more than others.

Any water spell will be useful against them and knockback jinxes can also be used.