I have a 10g tank that has had a group of 8 Rasbora Espei, 7 Corydoras, a single male Betta and a lone Ghost shrimp. The all work well together and dont bother one another. The Espei are a great looking small schooling fish and the Corys regulaly spawn. Just make sure you keep to a good routine with the cleaning and you'll do great.
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