My Fahaka puffer LOVES me. And I imagine everyone on here that has one, or an Mbu will say the same thing. They are friendlier then dogs. And they like it in their glass cages. They like to shred crawdads, and mash clams. If I am sitting in a chair watching mine and someone comes in the room I know it. He goes away until he is sure they aren't going to kill me. He just barely reacts to my wife.
Some fish like their little glass cages. They are safe, well fed and comfortable. My puffer eats the same kinds of things he would eat in the wild. He has a 150 all to himself. What a life.
Fish aren't stupid. Almost all of my fish are exactly the same. Doesn't mean they 'like it' really. Maybe, maybe not. I haven't had any luck talking to them yet.
I have a 4' American Eel that will massacre a hand of anyone but me. He'll let me pick him up, pet him, you name it. He knows I feed him and I'm ok knowing that. My other fish are similar - they hide if it's not me.