Yesterday i've added a nice red betta to my 5 gallon tank with only 3 endlers in it already and here's what happened. At first once acclimated and released into the tank the betta was swimming happily all over the tank while the 3 endlers stayed away from him for a bit. Later the endlers start following and running away from the betta for a while before they got tired of him and swam around the mid and lower levels of the tank while the betta swims up and down alot and around certain decorations. He's always swimming into the current alot (i buffered it down with a thin sponge on the outake). Then when i tried to feed the betta one betta pellet the stupid endlers started playing soccer with it! they tugged and pushed the pellet around here and there knowing very well it's too big for them! I guess the betta then knew it was his and flared at them which they promptly ran away, unfortunately the betta chewed on it and spit it out after and did that again. now i have a pellet on the substrated making ammonia ( just great!). by late evening before I slept two of the endlers are swiming on their own together while there's this one stubborn one that constantly follows the betta and gets close to him and then runs away when the big fish gets close. no nipping so far, i hope they can all get along. Sleeping time when i turn off the lights isn't a prob at all since once the lights go out the endlers fall right to the substrate level and stay there while the betta stays around the very top level for sleeping. well.... that's my experience so far with endlers incase anyone wonders since i couldn't find anyone here that tried it. they are similar to neons in size also very docile so it wasn't that bad when put together. tiny colourful things and the betta just makes the tank even more vibrant.