Similar looking to a wild guppy, but Endler's Poecilia" are not the same as guppies (Poecilia reticulata). Meaning they are not the same species.
They can however interbreed with guppies and so hybrids are the offspring.
There are a few Endler dedicated website on the www where you can get more indepth information.
It's quite rare to find pure Endlers in the UK and most sold on places like eBay (unless class is clearly specified) will be hybrids of some kind.
Fish to keep safely as tankmates with Endlers are :
Ancistrus, corys, otos, most loaches, amano and bamboo shrimp and snails.
However, here are some of mine - they would probably be classed as P (Any fish of unknown origin but appearing to be an Endler's Livebearer based on the characteristics of size, shape and color will be considered a 'Class P' Endler).