Why is goldfish staying at the bottom of the tank and not swimming around. he is eating.?

There are several things that can cause a goldfish to sit at the bottom. One reason for this is if your goldfish has an internal bacterial infection;the outcome for this, if left untreated, is usually dropsy and eventually death. However there are several ways to affectively treat this: one way is to feed the fish a medicated food, the food should contain antibiotics, (most medicated foods sold at petstores do not contain antibiotics that are actually affective against bacterial infections, ) however one medicated food known to work well (and has three affective antibiotics) is "medi-gold"(goldfish medicated food). A second way to treat a bacterial infection is antibacterial injections, this method however should only be performed by a piscine vet. Goldfish may also sit at the bottom if they are suffering from an infestations of flukes(a microscopic flatworm). Almost all goldfish that are purchased have flukes and usually are immune to the parasite until their slime coat (immune system) is damaged or if they are stressed. An affective way to treat flukes is using one of the following: formalin,potassium permganate,Droncit, or fluketabs. Lastly one other cause for a goldfish to sit at the bottom would be if the goldfish has a deformed swimbladder; either the swimbladder did not form right or is full of water instead of air. Usually the only way to correct this is by consulting a piscine vet to surgically fix the swim bladder.