Stress

Stress

Like virtually every other creature on the planet, fish are subject to stress. But in fish, it translates to a far greater problem. Most of the fish deaths that occur in your aquarium will be the direct or indirect result of undue stress caused by poor water conditions, incompatible tankmates or rapid environmental changes. And when your fish are stressed, they are more susceptible to a wide range of diseases and medical conditions. In other words, stress can kill your fish.

Stress often goes unnoticed in an aquarium, so it is important to be aware of its symptoms. Watch for fish that are:

Lethargic or exhausted
Trying to jump out of the water
Acting frantic or darting back and forth
Hanging just below the surface of the water and breathing heavily
Less colorful than usual
Ragged looking with frayed fins or tails
Behaving strangely
Failing to eat

If your fish exhibit the symptoms of stress, it is imperative you begin searching for the cause. Start with the easy or obvious questions. Did you recently add fish to the tank that might not be compatible with your existing fish? Did you change the temperature or water quality? Did your air pump stop working? Did you forget to perform a scheduled water change? Did you change the amount of light or the kind of lighting to which your aquarium is exposed?

Any change in aquarium conditions is liable to have a strong impact. Even something as seemingly minor as a 2 degree per day difference in the water temperature can induce temperature shock, which in turn, produces stress and eventually kills fish. Of course, some species are more prone to these problems than other species.

In addition, be aware that poor diet, frequent handling and netting, especially poor netting procedures, are extremely stressful. Always use two nets when trying to capture your fish, and avoid chasing your fish around the tank. Instead, use one small net to herd them gently into a larger net.

If you have not recently made any changes to your tank and your temperature is okay, your best bet is to go through all possible causes of stress step by step.

Pollution or presence of toxins: Test your water for excess ammonia or nitrite/nitrate levels. Change the water and replace the filter.
pH: pH levels should be 6.0 to 9.0 for freshwater fish and 8.2 to 8.3 for marine fish. If your water is out of these ranges, slowly adjust the pH for freshwater fish by adding the proper chemicals to adjust alkalinity or acidity in the water. With marine fish, adjust the salinity of the water, which changes the pH.
Temperature: If you do have a problem, remember to adjust the thermostat up or down gradually, not to exceed one degree per hour. Also, check to make sure the aquarium lighting is not heating up the water. Do not put species of fish together in the same aquarium whose temperature requirements vary by more than 4 degrees. Before introducing new fish into the aquarium, float them on top of the aquarium water in a bag full of the water from their most recent home until the temperature adjusts.
Overcrowding: A good rule of thumb is one inch of fish to one gallon of water for freshwater fish, and one inch of fish to two gallons of water for saltwater fish. If you have an overcrowding problem, get another aquarium and divide the fish up. If you prefer to keep the community together, get a larger tank.
Decorations: If you've eliminated chemical causes of stress, add some more decorations so the fish have enough places to hide.
Dominant Fish: All aquariums have dominant fish. Make sure the fish in the community are compatible. Move incompatible fish to another environment.
Aeration and Strong Water Circulation: Check to make sure your filter is the right size for your aquarium.
Aeration: Adjust the flow of water so bottom matter is not stirred up, which decreases oxygen levels even more
Diet: Make sure your fish are not malnourished. Add some variety to their diet and vitamins, if necessary.

Stress doesn't always have an easy answer. You can attempt to treat the diseases and medical conditions brought on as a result of stress, but until you remove the source of the stress, your fish will not recover.

As with most diseases and medical problems, prevention is the best treatment for stress. Knowing the symptoms of stress and understanding the causes are the first steps in maintaining the health of your aquatic friends.