What Is The Function Of The Swim Bladder | Aquascape Addiction

What Is The Function Of The Swim Bladder

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We cover the ins and outs of a Swim bladder, what it is and it's function of giving fish buoyancy. If you questions around the topic then this article should help.

What Is The Function Of The Swim Bladder

While most fish that we keep in our homes are not all that big, they do certainly have quite the interesting anatomy. One of the things that you might be interested to know about is how fish, or some of them, control their buoyancy, or in other words, how they sink deeper and float higher up.

This is where an organ known as the swim bladder comes into play. Let’s talk about what exactly this swim bladder is and what the function of it is as well.

What Is A Swim Bladder

Most bony fish have swim bladders, but many cartilaginous fish do not. The swim bladder is also known as the air bladder, fish maw, or gas bladder as well. The swim bladder is located in the center mass of the fish and is a derivative of the digestive cavity of the fish.

It is a buoyancy organ, in simplest terms. So, in layman’s terms, the swim bladder is an organ used for buoyancy which most bony fish possess.

What Is The Purpose Of A Swim Bladder?

As you can probably guess, since the swim bladder is the buoyancy organ of a fish, its purpose is to help fish regulate their depth. Yes, some fish simply use their fins to swim up and down in the water column, but this uses quite a bit of energy, energy that fish sometimes just don’t have to spare.

Well, the swim bladder allows some fish to adjust their depth in the water using nothing more than some gas. The swim bladder is usually filled with oxygen, but can contain other gasses as well.

In other words, if a fish wants to sink deeper down, it will empty some of the oxygen out of the bladder, thus making the fish less buoyant. If the fish wants to rise to the surface, or just rise up higher in the water, it will inflate the swim bladder with more gas in order to increase buoyancy.

It is also shown that in some fish, if the oxygen in the water is at a low level, the blood stream of the fish may draw on the oxygen in the swim bladder to stay properly oxygenated.


If you were wondering how most fish sink and rise in the water column so rapidly, the swim bladder is how it is done. It’s actually quite a simple organ, one that most fish have and use to help make their daily lives just a little bit easier.