Sandy: Fish have a left or right preference when they dodge a predator. This is likely to allow them to use a specific eye and side of the brain to deal with the threat. To see the preference of your own fish, place an unfamiliar object in the center of your fish tank and watch which way your pet swims round it.
In my earlier life, I had a couple of Discus Cichlids. They had a lot of personality. They liked me to visit with them – come close to the tank and talk. Their little lips would move like they were talking to me, then take a break while I spoke.
Sandy’s year long journey – going from being a right-hander to left-hander, and Kelly’s parallel trip as a left-hander doing things as a right-hander.