From everything I've read, Endler's thrive at higher temperatures around. However, from everything else I've read and experienced shrimp thrive around 70 F. I wouldn't mix the two due to that. Also, I wouldn't put that much bioload in a 1/2 gallon. I didn't know you had Endler's. I'd say you're maxed out. Don't add anything else to that tank IMO.