Our fish Jimmy is a very active, young Jumbo Oranda. Normally he swims around the tank happily, and even comes up to suck our fingers and get his head stroked. However after being left alone (with filter and light on) for 24 hours over Christmas which professionals said would be okay he has stopped swimming around the tank and stays in a bottom corner of the tank as well as not rushing for food when it is put in like he normally does. He had a 25% water change a week prior but was completely fine in the run up to Christmas. It’s completely unlike him and we are very worried about him. Does anyone know why this could be or what we can do to help him get back to his normal self ?