I noticed many posting that Endler's can be kept in Shrimp tanks, and I thought I would clarify something given my own experience with them both.
Male Endler's have small mouths and short attention spans, yet are curious and active so they nip at almost everything in their fish tank. this behavior profile makes them relatively safe to keep with shrimp as long as the shrimp have somewhere to hide temporarily during an Endler's occasional short span of curiosity, so a bare bottom breeder tank with nothing but gravel would be a bad idea.
Female Endler's can have much larger mouths and will focus for a minute in pursuit of food. They are as curious and active as males thus they nip at everything in their fish tank. this behavior profile makes them hazardous for any Shrimp under 1cm in size, or they may take limbs off young shrimp. shrimp hiding places may not help since the females will pursue the shrimp soon after they come out of cover when foraging for food.
So I would like to make the distinction that Male Endler's may be safe for Shrimp and possibly even hiding fry, while Female Endler's will certainly put an "end" to anything they can fit in their mouths like whole shrimp fry and the limbs of lazy shrimp under 1cm.