We have a 10 gallon tank with 1 Betta. We have had the tank about 6 months. I made the mistake of completely cleaning the tank and changing all the water at once. I'm afraid that I shocked our poor "Fishy" (My 2 year old named him). I feel horrible. He is just laying at the bottom of the tank on his side. His gills, mouth and fins are still moving, but he appears to be struggling. He has been this way since yesterday. I have been trying to find information on if he will recover, how long it would take him to recover? If he can't/won't recover is it best to just let him pass on or euthanize him? I have been reading different ways but they all seem a little cruel. Thanks for the help.