Thank you so much for sharing your experience. Yes Now my lungfish is eating and I'm starting to learn about its behavior too.My marbled hasn't shown that shifting behavior, even though I have plants and lots of driftwood. If you provide clay sewer pipes or other hides, perhaps it will feel safe there and settle down.
I've only kept african lungs and one of mine didn't eat for 9 months when I first got him, even when I elevated the temp. But now he eats like a pig. If you just got your small south American lung, I'm sure he will eat when he feels safe.
Hope this helps.
Mine also shift drift wood around, moving gravels and up root my plant, worse case, he killed all the tank mate tooMy SAL constantly shifts stuff in my tank.
Drives me mental
Samaka, I like the idea of a clay pipe. Maybe he will be happy in one and leave the other bits in the tank alone.