Though I definitely feel there are certain species famous for their inactivity-my Endli like others mimicks driftwood most of the time-I do feel a lot depends on the individual fish, tankmates, frequency of feeds etc. I had a bloody inactive Delhezi until I let my Florida Gar go-very active now. I also had a palmas polli which was very quiet (but have kept pollis in the past which were always on the go).