Common Swim Bladder Disorders and How to Prevent Them
Nature works its best in all its creatures and bestows organs in the body of all living beings, plants, animals, and humans that are necessary to survive. The swim bladder or also referred to as the air bladder is one such gas-filled organ that is part of the body of fish that helps it stay in the required state of buoyancy without floating up. It is present in the dorsal coelomic cavity of fish and also aids in many other air bladder function.
Location of the Swim Bladder
The swim bladder is made up of two sacs in some and one in other species of fish. It is surrounded by a tough outer membrane and located in the dorsal cavity lying just under the spinal cord in the coelomic cavity portion of the fish. According to the fluid pressure the swim bladder contracts and expands.
What is a Swim Bladder and How Does It Work?
The swim bladder works in a similar fashion to the way planes move in the air and helps the fish to freely move in any way it intends to. When any object or in this case fish is in water, the fluid nature causes the organisms to experience two states of force: the downward pull of gravity and the upward push of buoyancy. Due to the difference in the fluid pressure at every point, there is buoyancy. The weight of the fluid displaced by the fish is equal to the force of buoyancy on it. But if the density of the fish, that is the weight of the fish, is greater than water, the buoyancy force does not consider the fluid displaced and the fish will sink.
To remain without sinking by the fluid pressure, the fish with the help of the swim bladder increases its volume and not its density. A swim bladder is just an expandable sac, the mechanism of it can be considered to be like a human lung. Via the gills, the fish fills the bladder from the oxygen collected from the surroundings and in this way it reduces its overall density.
With this filling of the oxygen sac, the weight of the fish does not increase, rather only the volume gets higher. With an expanded bladder that is inflated more water is displaced and buoyancy helps it rise on the surface level and it sinks when the bladder is deflated.
Function of Air Bladder in Fishes
The functions of the air bladder in fishes are mentioned below:
Maintaining buoyancy is the primary air bladder or swim bladder function.
Helps the fish rise and sink and keeps it alive and going.
Helps the fish move side to side freely.
Other hydrostatic activities.
Sound producing or a resonating chamber can also be referred to as phonation in a few species with an evolved secondary modification.
Maintains equilibrium with the surrounding medium under varying pressures.
Helps in maintaining posture and aids in swimming.
Causes of Swim Bladder Inflation
The causes of swim bladder inflation include:
With floating, fishes tend to rapidly eat and gulp air, leading to overeating and constipation, which affects the swim bladder.
Low water temperature.
Enlargement of other organs that are in contact with the swim bladder when they enlarge due to cysts and then the swim bladder no longer has space to expand and slowly loses its ability to function.
Inflammation of the swim bladder due to bacterial and parasite infection.
Sometimes it is due to a genetic defect.
Symptoms of Swim Bladder Inflation
The symptoms of swim bladder inflation include:
Distended belly
Struggling to maintain a normal position or stay there for longer periods.
Curved back.
Sinks to the bottom.
Stays afloat.
Floating upside down.
Loss of appetite.
Treatment of Swim Bladder Inflation
The treatment of swim bladder inflation can be treated by:
If the problem is extreme one can hand feed the fish.
Reduce the water flow current.
Cleaning the water regularly.
Keeping the water temperature between 78 and 80 degrees Fahrenheit.
Reduce water level.
If the swim bladder disorder does not respond to the treatment in a reasonable period after it gets affected then chances of recovery are slim and one has to watch the fish die.
Prevention of Swim Bladder Disorder
To prevent the swim bladder disorder, there are certain factors that are to be checked upon. They are:
Avoid feeding frozen foods.
Soak the dried foods before feeding them to the fish.
The water temperature can be put a little higher.
Trying to sink the food into the fish so it does not come out for a bite and have to gulp air.
Keep the fish tank clean by washing it more frequently.
Conclusion
The swim bladder keeps the fish thriving even with so much fluid pressure. The swim bladder is an important part of the anatomy of fish but many fishes which stay on the ground level of the ocean and do not require a swim bladder. The swim bladder disorder can cause the fish a lot of harm so one must be careful and try to protect and prevent it.
FAQs on Swim Bladder: Meaning, Function & Health
1. What is a swim bladder and what are its primary functions in fish?
A swim bladder, also known as an air bladder, is a gas-filled organ located in the body cavity of most bony fish (Osteichthyes). Its primary function is to act as a hydrostatic organ, allowing the fish to control its buoyancy and maintain a specific depth in the water without expending energy. Additionally, it plays roles in respiration, sound production, and sound reception in various species.
2. What is the key difference between fish that have a swim bladder and those that do not?
The main difference lies in their classification and method of buoyancy control. Bony fish (Osteichthyes) typically possess a swim bladder to achieve neutral buoyancy. In contrast, cartilaginous fish (Chondrichthyes), such as sharks and rays, lack a swim bladder. To compensate and avoid sinking, they rely on a large, oil-filled liver which is less dense than water, and on the hydrodynamic lift generated by their pectoral fins as they swim.
3. How does a swim bladder help a fish control its depth in water?
A fish controls its depth by adjusting the volume of gas within its swim bladder, which alters its overall density. To ascend, the fish adds gas to the bladder, increasing its volume and buoyancy. To descend, it removes gas, decreasing its volume and making it denser than the surrounding water. This adjustment is achieved in two main ways, depending on the type of swim bladder.
4. What are the different types of swim bladders found in fish?
There are two main types of swim bladders based on their connection to the digestive tract:
Physostomous: This type has a direct connection to the oesophagus via a pneumatic duct. Fish with this system, like carp and eels, can regulate gas volume by gulping air at the surface or expelling it through their mouth.
Physoclistous: This is a closed system with no connection to the gut. Gas is secreted into the bladder from the blood via a specialized structure called the gas gland and a network of capillaries known as the rete mirabile. Gas removal is handled by another area called the oval.
5. Besides buoyancy, what are the other important roles of the swim bladder?
While buoyancy is its main role, the swim bladder has other vital functions:
Respiration: In some primitive bony fish like lungfish, the swim bladder is modified to function as an accessory breathing organ or a true lung, allowing them to breathe atmospheric air.
Sound Production: Some fish contract muscles attached to the swim bladder, causing it to vibrate and produce sounds for communication.
Sound Reception: The swim bladder can amplify sound vibrations from the water and, in some fish (like catfish and carp), transmit them to the inner ear via a series of small bones called the Weberian apparatus, enhancing their hearing.
6. What is the evolutionary relationship between the swim bladder and lungs?
The swim bladder and lungs are considered homologous structures, meaning they share a common evolutionary origin. Current scientific evidence suggests that primitive bony fish first evolved lungs as outpocketings of the digestive tract to breathe air in oxygen-poor water. Over time, in one lineage of fish, these primitive lungs evolved into the modern swim bladder, specialising in buoyancy control rather than respiration. In the lineage that led to land vertebrates, these lungs were retained and further developed for breathing air.
7. What are the typical causes and effects of swim bladder disease?
Swim bladder disease, or disorder, is not a single disease but a set of symptoms affecting the organ's function. The primary effect is a loss of buoyancy control, causing the fish to float uncontrollably to the surface, sink to the bottom, or struggle to swim upright. Common causes include:
Mechanical/Physical issues: Constipation from overfeeding or improper diet can cause the digestive tract to swell and press on the swim bladder.
Infections: Bacterial or parasitic infections can inflame the swim bladder.
Physical Injury: Damage from a fall, a fight, or rough handling can impair its function.
