hi, i have a 20gal with fancy guppiesx3, black neon tetrasx4, glass catfishx1, ghost shrimpx4, hornwortx2 and 2 teeny, tiny guppy fry. do you think one of those little crabs you see at the LFS would eat my shrimp? i don't mind re-placeing the shrimp, (i think they're 20 cent each) but it could...