Hi, I have a Silver Dollar who's been breathing rapidly and he seems to be parallel in the tank with head faces tofarde bottom and tail towards top of tank. Visually I see nothing else wrong. Other fish seem fine, there is a good amount of air bubbles in the tank. 150 gallons 2 silver dollars, two ID sharks. 1 Plecko and that's it. Not sure if it's old age or if there's abything I can do. Any help is appreciated