It might seem crazy, but crabs that have a great difference in size are more likely to get along better because they will never fight over shells. For example, my largest crab is almost 3 inches across, my smallest crab is the size of the tip of my pinky.
https://www.myaquariumclub.com/purple-pincher-hermit-crabs-447820.html
Hermit crab. Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the approximately 1100 species possess an asymmetrical abdomen that is concealed in a scavenged gastropod shell carried around by the hermit crab.
https://en.wikipedia.org/wiki/Hermit_crab
Take the naked crab and dip him in water to wash the substrate off him. Then rinse out his old shell. Put him and his shell into a glass cup together, and put into the isolation tank and leave him alone. It keeps him from running around frantically (as naked crabbies do) and conserves his energy.
http://hermit-crabs.com/FAQ.html
Six families are formally recognized in the superfamily Paguroidea, containing around 1100 species in total in 120 genera. 1  Coenobitidae Dana, 1851 – two genera: terrestrial hermit crabs and the coconut crab. 2  Diogenidae Ortmann, 1892 – 20 genera of left-handed hermit crabs. 3  Paguridae Latreille, 1802 – 76 genera.
https://en.wikipedia.org/wiki/Hermit_crab
Most frequently, hermit crabs use the shells of sea snails (although the shells of bivalves and scaphopods and even hollow pieces of wood and stone are used by some species). The tip of the hermit crab's abdomen is adapted to clasp strongly onto the columella of the snail shell. Most hermit crabs are nocturnal. Environment
https://en.wikipedia.org/wiki/Hermit_crab
Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the approximately 1100 species possess an asymmetrical abdomen that is concealed in a scavenged mollusc shell carried around by the hermit crab.
https://en.wikipedia.org/wiki/Hermit_crab
Hermit crab species range in size and shape, from species with a carapace only a few millimetres long to Coenobita brevimanus, which can live 12–70 years and can approach the size of a coconut. The shell-less hermit crab Birgus latro (coconut crab) is the world's largest terrestrial invertebrate.
https://en.wikipedia.org/wiki/Hermit_crab
Hermit crabs can grow to be more than 6 inches wide. Ive been keepin hermies for 4 years and ive learned that u definetly want more than one hermit crab or elase it will seem like you dont have one at all. You could keep just 2 or 3 so they are really spoiled, or if you want a big happy family u can keep around 5. But no more.
https://www.myaquariumclub.com/purple-pincher-hermit-crabs-447820.html
As new crabs arrive they also inspect the shell and, if it is too big, wait with the others, forming a group of up to 20 individuals, holding onto each other in a line from the largest to the smallest crab.
https://en.wikipedia.org/wiki/Hermit_crab
However, crabs of that size are not usually sold, so if you buy smaller crabs, you could get away with 4, or even 5 if they are fairly small, for quite a while. Just keep in mind that they will eventually need a larger tank.
https://www.myaquariumclub.com/purple-pincher-hermit-crabs-447820.html
how big do hermit crabs get
Hermit crabs can grow to be more than 6 inches wide.