What Could Be the Cause of Low Oxygen in Fish Tanks?

Fish need oxygen in the water just as animals need oxygen in the air. Maintaining oxygen levels is an important part of maintaining a healthy aquarium. There are many things that can deplete oxygen in the water, and there are several ways to prevent oxygen from being depleted.

  1. Stocking the Aquarium

    • Each fish in your aquarium breathes oxygen. The more fish you have, the faster the oxygen will be depleted. Each species of fish requires a certain amount of space. Before adding fish to your aquarium, consult your local pet store or tropical fish books to determine how many of each fish your aquarium can hold. For example, fancy goldfish need about 10 gallons per fish. A young fish uses more oxygen than an adult fish.

    Filtration

    • Maintain adequate filtration. It is best to have a biological filter and a regular filter. As things decay in the aquarium, they use up oxygen. Debris from plants, waste from fish and uneaten food all contaminate the aquarium and deplete available oxygen. Use an under-gravel filter and an over-the-side carbon filter to cover both areas of filtration. Place air stones at the top of the tank to add oxygen and help with air circulation.

    Water Changes

    • Frequent partial water changes are essential for maintaining a healthy aquarium. Change 20 percent of the water every one or two weeks to keep the water at good levels. Excess ammonia and nitrogen in the water can deplete oxygen. Doing partial water changes allows the good bacteria to remain in the tank while reducing the levels of ammonia and adding new oxygen. Always use water that has been dechlorinated or let tap water sit in an open container for 24 hours before use.

    Plants and Temperature

    • Keep your aquarium at a constant temperature. Most tropical fish require a temperature around 72 to 76 degrees Fahrenheit. Higher temperatures have lower oxygen levels. Keeping your aquarium in the lower 70s helps retain oxygen in the water. Live plants give off oxygen in aquariums just as trees give off oxygen on land. Planting a few live plants helps keep oxygen levels higher. Seeing gasping fish is never pleasant. Maintaining the cleanliness of your aquarium will help keep your fish happy.