It depends on how large your bioload is, how much you feed and whether or not you dose ferts. I do 50% water changes every week because I have a ton of guppies in my tank, AND I dose ferts using a modified EI schedule.I'm not sure if the mosses were really the culprit. The mosses I have are anchor moss. I found 2 dead in the mosses.
To be safe, I have removed the mosses. I thought the fishes could swim through it, maybe I was wrong.
I'll monitor again for a few days....I just changed 20% of the water. How often do you change their waters?
Okay, this is funny though it makes some sense tooWhile it would be kind of hilarious if endlers were such pansies that they got tangled up in moss and died, I highly doubt that is the case. It's just not how nature works IMO. You can be fairly certain they died and happened to find their final resting place in the moss.