Goldfish are among people’s favorite fish varieties when talking about aquariums and fish tanks. Their bright color and round shape makes them look very cute and adorable. Most of the time people will see goldfish swimming and gliding in the tanks smoothly and seemingly playfully. But there are also times when people notice that some goldfish will swim with their bodies upside down. It is also common that these goldfish that swim upside down are near the water’s surface and seemingly struggling for their lives. The main reason for this is that these goldfish are probably sick or suffering from health issues.
One probable health issue that can make goldfish sick is a bacterial infection involving their digestive system. When this happens, the goldfish may lose their inherent ability to swim upright. Sometimes its their swim bladder that gets affected, and so the goldfish will have a hard time maintaining an erect or upright body position. With this health concern, the affected goldfish will always struggle to maintain his/her body in the normal position in order to swim from one part of the tank to another. But the digestive or bladder concern will make it difficult for the goldfish to literally carry its own body through the water. The tendency is that the whole body will flip over while the goldfish tries to swim. For the affected goldfish, it would feel like the weight of its tummy will suddenly shift from deep inside, and so it will start to turn upside down. Air is also involved in the health problem, and this why the affected goldfish will also float to the water’s surface. With so much going on in the bladder and/or digestive system, sick goldfish will then try to continue to swim despite the new orientation of their bodies which is upside down. Some goldfish will be able to survive this ordeal for several days while the unlucky ones will die within a few hours of struggling.