Swim Bladder Disorder (SBD) sometimes aka Swim Bladder Syndrom, or SBS
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Description:
Swim bladder disorder is a condition that a fish can obtain usually as a direct result of diet, but sometimes also bacteria or even a deformed bladder. Overfeeding is the most common cause, while not feeding enough variety is the second most common. It is not contageous, nor is it truly a disease, but more of a condition. It is by no means deadly, and does not directly cause pain to the fish, but is more of an aggrivation for it, in most cases. But stress can lead to other problems, so it is of course important to treat.
When a fish overeats, its stomach swells beyond its normal size, causing it to press against the swim bladder organ.
Constipation and/or lack of variety in the fish's diet can cause SBD. This causes swelling as food has difficulty passing through the fish, clogging up and causing the stomach or digestive system to swell and press against the swim bladder organ.
SBD causes the fish to lose control of its buoyency. They use their swim bladders to adjust the amount of gas contained within, giving them the ability to maneuver and swim. When they are affected with SBD, they will have problems swimming straight and will instead lay sideways and/or will have problems with staying beneath the water at all. They will sometimes try to jam their bodies underneath objects in their bowl/tank in order to anchor themselves down. When they do try to swim, it looks more like a shimmy.
SBD can also be caused by bacteria. If fasting (see treatment below) does not cure the problem after a few days, treat with an antibacterial medication.
SBD could possibly be caused by some type of rupture to the swim bladder. Dropping a fish, pouring water too fast into a tank, or an overly aggressive spawning partner or tankmate might rupture the swim bladder organ.
Treatment:
In cases of rupture, there is not much you can do other than keep the fish clean to help prevent a bacterial infection, and wait it out. It may eventually heal or it may not; cull or keep, your call. Not moving the fish around will help it to be more comfortable.
Otherwise, if you don't think rupture could be the cause, the best way to treat SBD (the key word is treat, not cure, it's not a disease) is to fast the fish for about 3 days. The lack of food will give the fish's digestive system time to process and purge, allowing pressure to gradually reduce from the swim bladder, allowing its swelling to go down. Even if not due to constipation this will not hurt, because adding food would put even more pressure on the organ. At the end of the third day, if the fish is still having difficulty, it may require longer to allow the swelling to go away, if the problem was due to constipation. A betta can, at extreme, survive for a month without food (this is part of natural survival technique) so do not fear not feeding your betta for a few days. They are very durable fish. At the end of the fasting period, if you really want to ensure the system is flushed out, you can feed a bite-size portion of a cooked, de-shelled, green pea to the fish. Or, daphnia can work as a natural laxative. This, too, will help to purge out the system.
If your fish does not respond to fasting, it may have a rupture or bacterial problem, or even permanent damage due to a defect. Resume feeding the fish, but be especially careful to never overfeed it... keep in mind that most likely it will be less active with this condition so it won't require as much food, too. Keep it clean and hope for the best.
Prevention:
Most importantly, be sure not to overfeed. A fish's stomach is roughly the same size as its eye. If you can envision how much food would fit in there, anything beyond is overfeeding. If you want to feed twice a day, split that amount in half to feed each time.
With bettas, it is important to feed the fish a variety of foods. Bettas are carnivores, requiring high protein but no plant material in their diet, which most other types of fish obtain from their foods to maintain balance. A common cause of betta SBD cases are pellets. Pellets are a common food fed to Bettas in order to provide a balanced nutrition in an easy format. While this is great, they are typically made with a portion of ash, which is hard for a fish to process. Additionally, pellets swell after they are wet so pre-soaking pellets can help. Older fish are more prone to get SBD; eliminating pellets from their diet entirely is not a bad idea. Be sure to feed variety. Not only do bettas enjoy this more, but it is healthier for their digestive system. Many people choose to skip feeding one day a week to help with this. Feeding daphnia periodically can help to keep things working properly for your betta.
In fry, SBD is often linked to overfeeding on BBS. This may be due to consumption of eggshells. So for fry, either careful handling of BBS or hatching and feeding decapsulated BBS eggs instead of regular, as well as being careful not to overfeed, are ways to prevent SBD. Indications in fry: they will look overly bloated and will "belly slide" along the bottom, as they are unable to swim off the tank bottom.
In some cases, the fish's swim bladder can lose functionality due to old age or deformation. The fish can still usually live out a perfectly healthy life despite this condition. If all treatment fails, there is no need to euthanize the fish.