Toggle Myth / Reality Myth “Only Fresh Fish Can Be Examined” There’s a common belief that if a fish dies in an aquarium, an autopsy is pointless. It’s often claimed that you must dissect immediately after death, otherwise nothing useful can be learned. The reasoning goes like this: fish decompose very quickly at room temperature — within minutes, tissues change, organs lose structure, and parasites either die or abandon the host. ...
Let’s say your name is Lena. Or Tanya. Or maybe Alex. It doesn’t matter — what matters is that you’re curious, willing to improve your work with aquatic animals, and finally have access to a microscope (congrats!). You even got some stains? Then let’s begin. ...
Toggle Myth / Reality Misconceptions In most cases, the disease is caused by supersaturation of water with nitrogen, less commonly oxygen. This typically happens when water is heated in closed systems where gases cannot freely escape — such as heat exchangers in power plants or boilers in hatcheries. Air bubbles in the water, on glass, or on plants are dangerous — they can block the gills of fish and cause death. External signs of gas embolism appear a few hours after fish are placed in supersaturated water. The higher the gas saturation level, the faster the symptoms develop and the sooner the fish may die. At lower saturation levels, fish may survive longer, and signs like the location and shape of bubbles become more variable. During necropsy of larger fish, foamy blood may emerge from blood vessels. Other signs include: hyperactivity, hypersensitivity to mechanical stimuli, loss of balance, twitching fins, scale erection, ray separation, corneal opacity, lightening or darkening of body coloration, loss of vision, exophthalmia. Causes may include: excessive oxygen production by plants, overly aggressive artificial aeration, or the use of untreated tap water. The disease develops in conditions of oxygen and nitrogen oversaturation. Oxygen entering the bloodstream in excess forms tiny bubbles that block blood vessels. When bubbles enter capillaries, they are often larger than the vessel’s diameter, and the heart is not strong enough to push them through — resulting in blockage. The diagnosis is based on clinical signs, necropsy findings, and water analysis, specifically the level of dissolved oxygen. Scientific Perspective Gas Bubble Disease (GBD) is a pathological condition in which free gas bubbles form inside the blood and tissues of fish. These bubbles can lead to ischemia, gill dysfunction, vascular rupture, and even death. It is common — even in professional literature — to see oversimplified explanations like: ...