i would have to say my green spotted puffer is the smart one. he recognizes the food containers; he gets more excited when he sees clam or mussel shell than he does the bowl though he does get excited for the bowl. he also knows what a spoon is (i drop food into his tank using one). he chases the spoon to the top of the tank when im feeding him. he also knows when its water change day; he paces his back right corner until the water is changed. he also comes up and begs for treats when we come sit by his tank. he comes right up the glass and eyeballs you. and hes figured out that the cherry shrimp tank is right next to his tank. hell watch the cherries, then swim around his tank looking for snacks. its really funny. the best thing he does though is napping. hell curl up under something and nap. but if you look in at him while hes doing this, he will roll a single eyeball at you with an attitude of "what the f--- do you want?!" its hilarious
