Sinking crab pellets twice a week for the hermits. Until you have fish and are actively feeding them. With no alage or food going into tank hermits may turn on each other or the snails. Crab pellets are cheap and it doesn't take many. Once they hit the water the crabs will find them by smell.
It's what I do for my 210gallon that's currently fallow.
If you use them be sure not to feed to many and literally only like twice a week is enough.
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One small bag Will last several months. You certainly wouldn't run out before adding fish.
Available online, most lfs or petco- is where I grabbed mine.