How to Diagnose Fish Tank Symptoms

Symptoms of a fish tank problem can come from several sources, ranging from overfeeding to equipment failure. The tank and filter size, number of fish and tank-cleaning frequency also are factors. Generally, a little investigating along with knowing what to look for will pinpoint the issue so you can take steps to correct it. Fresh and saltwater tank symptoms may differ.

Things You'll Need

  • Nitrite and ammonia test kit
  • pH test kit
  • Gravel cleaner
  • Aquarium thermometer
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Instructions

  1. Diagnose Fish Tank Symptoms

    • 1

      Determine the symptom(s) your fish tank is exhibiting. Is the water cloudy, too cold or have a bad odor? Is the water green instead of clear? Are the fish showing signs of illness?

    • 2

      Change the water and clean the gravel with a commercial gravel cleaner if the water is green, indicating it has algae floating in it. Eliminate bright light near the fish tank to reduce the chance of algae redeveloping. Block sunlight from the room the fish tank is in, or move the tank to a darker room. Either don't use the overhead light in the tank cover, or install a color-enhancing bulb made for aquariums.

    • 3

      Look into the tank from the top if you suspect cloudy water. Your problem may be a film on the inside of the glass that's giving the illusion of cloudy water. If you determine the water in the tank is cloudy, test the ammonia and nitrite levels in the water; both levels should be zero. Look for uneaten food at the bottom of the tank, which would indicate you may have overfed your fish. Examine the filter to see if it's clogged and needs replacing or isn't large enough to handle the number of fish in the tank.

    • 4

      Consider several possibilities if your fish tank emits a bad odor. Check for dead fish and plants or excess food in the tank. Look at the glass, water and gravel in the tank to see if they're clean. An odor can develop when you don't clean a fish tank often enough. Determine if there are too many fish for the size of your tank; too many fish or a filter too small to handle the number of fish in the tank can also cause an odor.

    • 5

      Check the water temperature with an aquarium thermometer. If the water is too warm or too cold, check the heater for problems. If the heater is working properly but the water is too warm, remove exterior heat sources or consider installing an aquarium chiller.

    • 6

      Check the pH (acid) level in your saltwater fish tank if your fish are showing signs of illness. The pH level should be between 8.1 and 8.3, as indicated in the Saltwater Aquarium Guide. A low acidity level caused by fish waste and high levels of carbon dioxide can kill your fish. Change part of the water and/or aerate the fish tank to maintain the proper pH level.