I just bought a shoal of 4 marbled hatchetfish for my planted aquarium today. After dinner I noticed one of my hatchetfish having a curved spine and trying very hard to straighten it. The spine and tail start to curve downward after its dorsal fin. It straightens when the fish swims but curves again when it rests. The other 3 do not have this problem. Should be concerned about this? Could it be Fish TB Mycobacterium Marinum?