Would raising the temperature of a 100 gallon fish tank 5 dgrees kill salt water fish?

Yes, raising the temperature of a 100-gallon saltwater fish tank by 5 degrees Celsius (9 degrees Fahrenheit) can be fatal to the fish. Saltwater fish are adapted to live within a narrow temperature range, typically between 75-85°F (24-29°C). Sudden or significant changes in water temperature can cause stress, illness, and even death in fish.

A 5-degree increase in temperature can be particularly dangerous for saltwater fish because their bodies are more sensitive to temperature fluctuations. This is because their metabolism and immune system are finely tuned to function within a specific temperature range. When the water temperature rises too high, it can disrupt these processes, leading to organ failure and other health problems.

Additionally, saltwater fish have limited ability to regulate their body temperature. They rely on the water to maintain a stable internal temperature. When the water temperature rises, their bodies can overheat, leading to a condition known as heat stress. Heat stress can cause a range of symptoms, including increased respiration, lethargy, loss of appetite, and impaired immune function. In severe cases, heat stress can lead to death.

To prevent harm to your saltwater fish, it's important to maintain the water temperature within their ideal range. This can be achieved using a reliable aquarium heater, and regularly monitoring the temperature with a thermometer. Avoid sudden temperature changes, and gradually adjust the temperature as needed to prevent stress and illness in your fish.