I just picked up a cherub today for one of my nano displays(24g) it was in a 13g display tank at the LFS for months, im not an expert here but id say the cherub wouldnt be much different than the sixline in a 14g nano if anything the sixline would be “worse” ive seen sixlines as big as 4 inches in frag tanks and no cherub bigger than not even 3 inches, my sixline’s name is kanye west he as major attitude and is not a calm fish by anymeans very darty and can be a bully i cant imagine him stuck in a smaller display with other fish hes currently in my 24gallon with the cherub and a tailspot blenny i plan on moving him into my 120gallon i just need to build up the courage to catch him but im just talking from personal experience! id say youd be okay with the cherub there aborable little fish you wont regret it if you end up getting one