This has been my experience with them in my 45L where I originally had 11, they swam as a little school quite often for a few months and then stopped and hardly ever moved, and it seems at some point 4 of them died. I felt like they really needed more space, in the 45L a big bit of wood dominates so there wasn't as much free swimming space as I'd like. I've seen videos on youtube where they were in big groups and wondered whether that would make a difference too, I like the idea of big schools of tiny fish. And also keeping them with tetras, as I've noticed a significant increase in confidence in my other fish with the tetras around acting as dither fish, and making sure there's lots of shady areas and leaves (they used to love hiding in the leaf litter)Much as I love them, I wont get them again for this very reason. They are amazingly cute, but like the x-files, I have to believe they are out there in my tank as I only catch glimpses of them. There are 10 or so in my 50l tank but I actually believed them dead for a long time, until for some reason the whole group came out of the foliage a month or so ago and to my surprise all were still present. They all looked happy enough, not skinny, so I'm guessing they are just happy where they are, but for me it means I'll get fish a bit less shy next time, because this is somewhat extreme I see one or 2 occasionally resting here and there but thats it
This group of 26 in my bigger tank is a test to see if they will still become lazy, or if more space, larger numbers and a scape designed to make the fish feel safe actually will make a difference long term. I'm hoping it does, but I know they might just end up being rather shy anyway. I'm used to it though, I'm lucky if I see a kuhli a few times a week! They are super active in the tank today, still all over in varying sizes of groups, they are really using the whole tank top to bottom front to back, very funny though Ms Apisto is not pleased that she keeps having to shoo them away from her babies.