No disrespect to the freshwater universe, but in my recent transition from freshwater to saltwater fish, I was unexpectedly stunned by the fascinating diversity of personality that I rarely saw previously. Freshwater fish seemed to have....well....almost no personality. Maybe others have a different experience. But I really find the behavior differences these saltwater fish to be so interesting. The following is how I would describe personalities in my tank by type.
Chromis - Attention Deficit and Hyperactivity Disorder (ADHD). Interest level 4.
Azure Damsel - Greed. All about getting to the next meal first. Interest level 3.
Royal Gramma - Boring, boring, boring. Might as well be freshwater. Interest level 2.
Fire Fish - Jacqueline Kennedy Grace. Interest level 6.
Coral Beauty - Cowardly Lion with Good Witch beauty. Interest level 5.
Blue Tang - Schizophrenic, Bipolar. Interest level 7.
Diamond Goby. Louie De Palma (Taxi) - Interest level 7.
Clownfish - David Spade and Chris Farley. Interest level 9.
Wonder what you see.........
You are correct about the individual personalities being very different from Freshwater to Saltwater. There are a few exceptions (ie Koi, Parrotfish), but for the most part saltwater fish definitely are more interesting individuals. Here my observations on my tank
One Spot Foxface-The Ultimate Spaz. He will be fine and then something will spook him and he changes color and dashes off and hides for a few minutes. He later comes out slowly poking it's head out with a "Seriously, is the mouse gone yet?" type behavior. He is also a the resident chipper/shredder for seaweed. Everyone is stunned by how it devours it. He also does this goofy slow swim with his snout pointed upwards.
Melanurus Wrasse-Greed, Curiosity and Monkey-See-Monkey-Do. It is definitely Greedy and hates the Leopard Wrasse at feeding time. They tolerate each other for the most part otherwise. It definitely feels entitled to just about anything and will expolore and try just about anything. It's Monkey See, Monkey Do aspect came about with my Coral Beauty and former Yellow Tang chowing down on Seaweed. Prior to that it had little to no interest and now it joins the frenzy on a daily basis as if I were handing it a shrimp buffet. It also does a periodic "Dance for it's Dinner" when I get near the tank from time to time.
Blue Star Leopard Wrasse-The most curious and people friendly fish and opportunistic sneak. Due to the hassle that my Melanurus gives my Leopard Wrasse at feeding time, it has become very opportunistic at feeding time and will dart in and grab food bits and literally lead all my fish on a chase around the tank with large chunks of reef frenzy hanging out of it's mouth. I have even seen it rip food out of my Foxface and Coral Beauty's mouths if they don't get it in all the way. When I go and clean the tank, and have to stick my hands in, all the other fish hide. The Leopard Wrasse actually will swim inches away from me scrubbing my rocks with a toothbrush and is the only one to come out and hang out when I have house parties with lots of people around.
Pajama Cardinal-Probably the most freshwater like fish I have. Not much personality and it just hangs out although it does fit the "little fish with a big mouth" as it can gobble down bits of food that are too big for the other fish.
Coral Beauty Dwarf Angel-Funny and Curious Little Nibbler. Likes to hang out with the rest of the other fish and is the only Dwarf Angel I have seen that is cool with other fish hanging out in it's cave. The Foxface, Melanurus and even occasionally the Blue Star Leopard go through there and it doesn't care much. Occasionally it gets irritated with the PJ Cardinal being in it's way and does an "Outta my way" charge at it but that's the total extent of it's aggression. He also likes trying to give me the fish equivalent of "puppy dog eyes" when it is hungry.
Conversely my Glofish in my Freshwater tank at work occasionally chase each other and will respond if I hold the Flake Food jar up to the tank, but that's about it.