I Don't Know What is Happening to My Fish…?

One of my fish seems to be dying. It has two small gashes in its side. BTW, it is a Glo-fish. One side of its stomach is bigger than the other. When it swims, it is pointed diagonally up. Its tail and its side fins seem to be the only things making it move. Its tail move in tiny fast swishes, yet it goes so slow. All of its other fish friends are fine and swimming much faster. Its not eating… and it normally is the one to get all of the food first. I do know that it is female. I do not think that the other fish are biting its sides. I dont know if its dying of old age. What do you think? Please help. I have had my fish for just over a year…

Suggestion:

Seems like a swim bladder disease. Feed him mashed peas and live food. STOP PELLETS! And always soak the pellets in tank water for 10 minutes before feeding, this avoids further swim bladder disease. You may give Epsom Salt, Magnesium Sulphate @ 1/2 tsp per 10 litres of water. Good luck. Email me for further query. Thank you.