It's like H. comes, while some survive, many do not, and in far worse percentages than we experience with other species.
Also, kelloggi are very often misidentified, almost as bad a kuda, so what your lfs has MIGHT not be kelloggi.
If it is kelloggi, they are lucky to have them last that long.
The "org" has a current thread plus many older threads about H. kelloggi and their problems.
Dan Underwood of Seahorse Source has not brought in comes and kelloggi as he worries about contamination spread from tanks with those in them, to the tanks of his regular species.