Mixing Tetras?

Shoaling fish are those that live in groups of thousands in the wild. When there are only a few of them, it switches on the instinct "where have my mates gone; they must have been eaten; I'd better be on guard in case that predator comes back for me" That constant watching for the predator stresses a fish and makes them more susceptible to disease. It was thought that fish 'lose count' at around six which is why six was chosen as the minimum number for a species of shoaling fish.
Shoaling fish of different species will shoal together out of desperation, being in a shoal of some sort is better than no shoal at all. If there aren't enough of their own species they will still get stressed, just not quite as much as if there weren't any other fish at all for them to shoal with.

What I'm trying to explain is that mixed shoals are better than nothing, but nowhere near as good as a shoal of the same species.



And just to warn you that with 6 danio (zebra and leopard are the same species) and 6 glowlight tetras you tank is almost fully stocked (84%). Even a shoal of something as small as the ember tetra would push you over 100%. You might get away with 3 or 4 endlers but you would need to keep on top of your water changes.

Do you have a Maidenhead Aquatics near you? They usually have endlers in stock.