Alright. Last post before bed.
Sail fin plecos become very lazy as adults. Most of them prefer to stay in a cave and wait for food to come to them.
A healthy, adult electric blue acara is a fish that everyone wants. Not everyone can keep one for various reasons, but everyone wants one. Also, eba's can become incredibly persistent when it's time to breed.
The nicaraguan cichlid usually keeps to itself. Content to dig holes all day. When disturbed by other fish, or conspecefics, they can become very aggressive and the embodiment of Wrath.
Discus are envied by everyone. Many try to keep them and fail, or can't afford them to begin with. Those who do truly succeed are usually placed on a pedestal.
For greed, the Malaysian trumpet snail. They eat everything, reproduce at an astounding rate, and generally simply refuse to die. I believe their one goal as a species is to overrun a tank and consume all forms of life they possibly can.
Silver aros: I don't know if you've ever kept one, but they will eat, and eat, and eat. Mine literally ate himself to death. There was an adult bushy nose pleco in the tank with him. He ate it, and it killed him. Fairly good example of gluttony.