Fish need oxygen to live, just like us humans. They take in oxygen from the water around them, or sometimes from the air, and breathe out carbon dioxide. This is similar to how we breathe in air for oxygen and breathe out carbon dioxide.
However, not all aquarium fish breathe in the same way. There are two different methods that fish use to get the oxygen they need to stay alive.
These two methods are:
- Gill Method, and
- Labyrinth Organ Method.
Let’s take a look at each of these methods.
Gill Method
Unlike land animals, fish extract oxygen from water using a complex network of blood vessels in their gills.
Think of gills as the fish’s equivalent of human lungs, but more effective. Humans extract roughly 25% of the oxygen from inhaled air, whereas fish can extract up to 85% of the oxygen from water.
Water enters the fish’s mouth, flows over the gills, and the oxygen is absorbed by the gill filaments. The water, now low in oxygen, is then expelled.
It’s important to note that the type of fish and their energy levels significantly impact this process.
For example, the freshwater danio, a high-energy fish, must consistently swim to push water through its gills and secure the required oxygen.
So if you keep such fish in a small tank, they will run out of oxygen very fast which can prove fatal.
That’s why you need to ensure that the tank you get for your fish is big enough for them to swim around comfortably.
Each type of aquatic animal needs a different size and shape of tank, so do some research about the specific needs of the fish species you’re planning to keep.
Labyrinth Organ Method
This is a unique breathing method used by a group of fishes called anabantids. These include species like bettas, gouramis, and paradise fish, found in Asia and Africa.
These fish usually inhabit waters in the wild with low oxygen levels and so have evolved to breathe air directly from the atmosphere with a specialized organ called the labyrinth.
Located in the head, behind the gills, this organ is a maze-like structure of rosette-shaped plates filled with thousands of blood vessels.
These vessels extract oxygen from the inhaled air, trap it in a sponge-like structure, and gradually incorporate it into the bloodstream.
As a result, anabantids can take in oxygen directly from both air and water.
This adaptation enables anabantids to survive in smaller aquarium spaces than most fish. However, it doesn’t mean that they should be kept in confined conditions.
Like other fish, they generate the same amount of waste and require sufficient space and proper filtration to live healthily.
Betta fish are often sold in small jars to prevent fights between males. But, this isn’t an ideal practice for you to follow.
Don’t keep labyrinth fish in small decorative bowls or vases. Instead, give them a large, well-kept aquarium. Their air-breathing ability doesn’t eliminate their need for a suitable aquatic habitat.
