It's fascinating to work with animals in captivity, because we can learn a lot; physiological data that can't be collected from wild individuals. Veterinary care. The fact that sometimes moving a stick that an eel liked a lot will result in them having a tantrum for six months

(Zoos and aquariums prevent extinction pass it on) https://www.aza.org/from-the-desk-of-dan-ashe/posts/how-zoos-and-aquariums-protect-endangered-species

Okay A LOT of people are asking for description of eel tantrum:
1) all food is a personal insult now
2) dramatic side-lying; I've died, I'm dead, woe is me, etc.
3) multiple eels all cram under other sticks that were not moved and stare distrustfully at moved stick
4) bullying

Additional notes: The stick was moved to put MORE stick for better eel habitat. The most heinous crime ever committed