I work on the principle that if it fits in a fishes mouth then they will try to eat it. I keep a huge RCS colony with 50+ assorted tetras. The fish definitely pick off some of the young but don't even attempt to go for the adults. Give plenty of cover for the young shrimp, moss is ideal as the fish can't get deep down into it. As for the gourami, it may take larger shrimp. I'd stick to tetra size fish if introducing RCS.
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