
They are very hard to raise in captivity. During my aquarium years I never dared to try. I left that to the seasoned experts. Every single thing, water balance, nutrients, metal content, filter media, temperature, plants, substrate, food, lighting, etc. has to be very specific and perfectly maintained or they’ll die. So Clea feels her own situation is exactly like a sunfish. Definitely an apt comparison.

As another add on to the sunfish part, due to the details listed above, the term sunfish is given to characters that are high maintenance and die too easily and for sometimes dumb reasons. This internet slang/term started due to the survive mola mola game that features you raising a sunfish who dies for stupid reasons like not withstanding the impact of falling back to water after jumping out. So, the game got popular(not anymore) and later on koreans started using it as a term for charas who die too easily. A great example of a sunfish character as well, is Yoo Joonghyuk from orv.
Kinda long but I wanted to share what I know.(≧∀≦)
Why sunfish? I guess it's sort of a meme or something. Last time I checked, sunfish is a huge but pretty docile carnivorous fish. ╮( ̄▽ ̄)╭
I don't know about you but I'm certain that the duke's face and hairstyle changed, made him look much younger. (〜 ̄△ ̄)〜