That is a good point and my tank is so new. I am supplying the food right now and hoping that the algae with start here soon for them. I hope I don't lose any. I didn't know about the extra shells that is great advice. Do you order them off line or where did you get yours?I would not add any of these hermits crabs/ snails until you have built up some algae for them to eat, altough they do eat scraps and supplements the survival rate in a new/ clean aquarium is poor.
Maybe wait until your aquarium is more matured (I cycled my aquriam empty for 8 months) and then clean up crew (cuc) when you have enough algae for them to graze on
I have Dwarf red legged, Dwarf blue legged, electric blue, Halloween hermit, various snails and various crabs (cuc)
Besides algae for them to eat/graze you need to also provide plenty of shells/ new homes... This will help with aggression towards each other
I don't think you should introduce any cuc at this stage of your aquarium