Defientely get more than one if you can!
I have my "quartet" since Christmas and have noticed a few interesting traits so far:
1) Yes, these are calm, easy going fish
2) They seem to be always hungry but unlike other cichlids they are not as wiling to explore new foods. Snooks will often starve themselves for days before accepting a new pellet or what not but once they do start eating it, they will almost leap out of the water to grab some
3) Unlike most other CA cichlids, these are quite sensitive to water paramters refusing to eat even when there is a slioghtest fluctuation
4) They are incredibly messy. Far worst in my opinion than oscars and other large cichlids. You also have to use a slightly different technique when feeding them: Since their mouths are so big and they are generally very greedy, petenias will often gourge themselves with food, stuffing their protrusive jaws to the limit. The problem is that while they have such huge mouths, their throat openning are proportionate to their overall size. As a result, snooks will often continue grabbing pellets or flakes as long as you are dopping them in, then swim for a while with a full mouth, and suddenly release all the food half an hour later when they realize that the load is impossible to swallow. Needless to say, this creates an enormous mess! Plus, the turds they produce are the size of my cat's (and I mean a feline here)!
5) Males are definetely more outgoing than the females who tend to hang in the back of the tank and in their own territory. Males generally are free roamers
Get the fish man. Make sure your tank/pond is large enough and that you have sufficient filtration. You will like them for sure
it might not have seen it was a food source just some leaves!