How to Determine If an Aquarium Is Overcrowded or Not

You know that your fish can live in close quarters, but sometimes it can be difficult to tell when space in your aquarium is a little bit too tight. This is especially true if you have several different types of fish in your tank. Some breeds of fish need more space than other breeds. An overcrowded tank can lead to dirty water, parasites and health problems for your pets. You should make sure that you do not have too many fish in your aquarium so that you can keep your pets healthy and happy.

Things You'll Need

  • Water sample
Show More

Instructions

    • 1

      Look for fish breathing at the surface. Overcrowded tanks do not have enough oxygen and fish may try to breathe atmospheric air to compensate.

    • 2

      Look for fish fighting. Some species become aggressive if they do not have enough space. Look for fish pecking at each other or fish with bits missing from their fins.

    • 3

      Look for dead fish. Overcrowded fish may kill one another. Overcrowding also leads to problems like parasites, lack of food and lack of oxygen. All of these situations can be deadly.

    • 4

      Measure your fish. If your fish won't grow, they could be underfed and overcrowded.

    • 5

      Look for brackish water. If your tank is constantly dirty, you have too many fish. Overcrowding can overwhelm your filter and your pump.

    • 6

      Take a sample of your aquarium water to your local aquarium store and have the chemistry tested. A healthy tank should have zero ammonia and nitrite, low nitrate, high dissolved oxygen and a stable pH.