Unlocking Aquarium Success: The Crucial Role of Dissolved Oxygen Levels for Healthy Fish - A Comprehensive Guide

As we all know, oxygen is vital to all animals. Therefore, thinking about the oxygen levels in the aquarium is very important. Dissolved oxygen (DO) means the oxygen available in the water. In an aquarium, DO should be at least greater than 5mg/L (milligrams per liter). A healthy aquarium should be greater than 8mg/L. There are digital meters available to measure the DO level in the water.

Suppose you see most fish swimming on the top surface of the water for a long time. That indicator tells you the DO level has gone down in the aquarium. If it goes further down, that can be life-threatening to our fish.

Figure 1: swimming on the top surface of the water

Different parameters cause to reduce the DO levels in the water.  We will consider the main parameters that drive a reduction in the DO levels in the water.

High Temperature

High Temperature is the main factor that affects the DO levels in the water. When the temperature increases, DO levels in the water go down. Therefore, we have to make sure to keep our aquarium temperature below 28C^o.

Nitrification Process

The nitrification process consumes DO in the water. The following formula shows you that.

Removing the fish waste occasionally by siphoning the aquarium will reduce generating NH₃ in the water.

What happens if DO levels decrease in the water?

• Growth rate of the fish can decrease

• Reproduction rate can be decreased

• Directly affects the immune system of the fish and quickly affects diseases

• Gills of the fish can damage.

• Toxic presence in the water can increase. (Ex: when DO reduce, it will reduce the  nitrification process, increasing the ammonia present in the water, which is toxic for fish).

How to increase the DO levels in the aquarium?

Aeration the water

Aeration is one of the main methods that we can introduce to increase the DO levels in the water. Aeration is essential if the aquarium has a high density of fish and plants.

Figure 2: Aerating the aquarium

Water changing

Figure 3: Water Changing

We can increase the DO levels by changing the water in the aquarium. Remove old water by siphoning once a week. Adding new water will reduce the ammonia in the water, and it will help to increase the DO levels in the water, reducing the oxygen consumed for the nitrification process. For more information about the water changing process, you are invited to read the aquarium article in this blog.