Hi, About a year ago I bought a gold fish. He was doing really well and grew quickly, so I moved him into a 20G tank with a 50G filter. I usually do 10% weekly and 25% monthly water change. This is the only fish in the tank. A few months ago the fish got sick. Around the same time we adopted 2 dogs, but I'm not sure if they are related. The symptoms included:lack of energylack of appetitecloudy eyesfin rotstaying on the bottom I tried the natural remedies Melafix and aquarium salt, but they didn't help much. Next I tried API tetracycline and it appeared to work, but it didn't last. Next I tried erythromycine, but that didn't help. I also tried API general cure and API fungus cure. In addition to the original symptoms, there are a couple of new ones: what looks like hemorrhaging on the backwhen he tries to eat food, he squirts the food out of his mouthsometimes is looks like his jaw is stuck open, but it only lasts a few seconds and I don't see any gravel of food stuck in there I have already spent close to $100 on this $6 fish, but I'm willing to try one or two more antibiotics before giving up. There is a huge selection of antibiotics available online, but I'm not sure which one I should try. I would really appreciate any help. I tried to post some pictures, but there's something wrong with the forum link. I have sent the error message to the webmaster. I'll try to post the pictures somewhere and paste the link here.