Welcome to FF! I agree with Blue Cray, you might want to tweak the stocking of the 20gal. Also, fiddler crabs are brackish and require land, and they should really not be kept in a freshwater tank. Lastly, your cories need a shoal of at least 6, but albinos are too large for a 20 gallon.
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current setup:
5.5 gallon low-light planted tank
-nothing....thinking a mini-community.
for reference: my name is Julie 
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