(slang) dependent child or elderly person, most commonly used to refer to children that have been raised by parents who have expended a lot of blood, sweat and tears (originally a mythical fish that would cause one to vanish when eaten)
Definitions (粵典–words.hk)
名詞
傳説生物，據講同生魚一樣樣，但係有四隻腳，食咗會全身啲骨溶晒噉死（量詞：條／隻） a legendary creature that looks exactly like a snakehead but with four legs, which is said to be deadly poisonous if mistakenly eaten as it can "dissolve one's bones"; literally "bone-dissolving dragon"
名詞
對未自立嘅仔女嘅戲稱，用嚟強調養大佢哋好辛苦（量詞：隻／班） child; dependant child; used to emphasise the hardship in bringing up the child(ren)
隻化骨龍仲細嗰陣，就望佢快啲大；到佢真係大個嘞，又有啲唔捨得。
只化骨龙仲细𠮶阵，就望佢快啲大；到佢真系大个嘞，又有啲唔舍得。
zek3 faa3 gwat1 lung4 zung6 sai3 go2 zan2, zau6 mong6 keoi5 faai3 di1 daai6; dou3 keoi5 zan1 hai6 daai6 go3 laak3, jau6 jau5 di1 m4 se2 dak1. When the "bone-dissolving dragon" was still a kid, I wanted him to grow up faster; now that he is grown-up, and I miss that time.
Definitions (Wiktionary)
noun, Cantonese
a mythological creature that resembles a snakehead (Channidae) but has four legs, allegedly able to cause one's bones to dissolve if one were to eat it (Classifier: 條／条 c; 隻／只 c)
noun, Cantonese, figuratively
one's own child, often one who is difficult to bring up (originally because of being a big eater, thus becoming a financial burden for parents) (Classifier: 條／条 c; 隻／只 c)