Fish swimming vertically top three causes and easy solutionsFish swimming vertically can surprise Aquarists as this is completely understandable because fish swimming straight up and down isn’t normal behavior. If your fish are behaving likewise and you’re in serious need of guidance, you’ve come to the right place.

Read out fish guide, as it  will highlight the reasons why fish can change their swimming pattern from horizontal to vertical and list out several helpful treatments to help your finned friends thrive!

What Does Fish Swimming Vertically Mean?

Fish swimming vertically is a phrase used by aquarists to describe a change of pattern in swimming behavior. Fish morphology naturally helps them move forward in horizontal patterns instead of vertical ones. That doesn’t mean fish can’t swim vertically, just that when they do, there’s generally something wrong.

Why Is My Fish Swimming Vertically?

It may sound shocking, but the ‘fish floating vertically‘ phenomenon is somewhat common. There can be several reasons behind why fish can take to swimming vertically. Some causes are pretty easy to tackle, while others require careful handling. Here’s what some of them are:

– Gestation

If your aquarium houses male and female pairs of live-bearing fish species like Mollies, Guppies, or Mosquitofish, it’s possible your fish is swimming vertically due to being pregnant.

It’s pretty standard among some fish species to swim vertically and go off their food when spawning draws near. Others can also take to swimming near the bottom of the fish tank.

If swimming vertically is tied to your female fish being pregnant, then there’s nothing to be concerned about. However, it’s best to watch out for other pregnancy symptoms to ensure no other health concern is involved. For example, live-bearing species exhibit signs like bulging bellies and a darkening gravidity spot.

If you’re sure your fish is pregnant, there’s not much you can do to help it swim naturally until the fish gives birth or lays eggs. Once delivery or spawning occurs, your fish will go back to swimming naturally.

– Stress

Fish owners can be a little surprised to learn that their finned pets are susceptible to stress. After all, what do fish have to be stressed about? The truth is fish can experience stress for numerous reasons, ranging from bullying to inadequate water parameters.

Stressed fish can exhibit several symptoms, including odd swimming patterns (i.e., fish swimming nose down), rubbing on gravel or tank decorations, lack of appetite, etc. But, since there can be multiple reasons behind stress development, you’ll need to get to the source before helping your fish get back to normal. Here’s how:

– Water Parameters

Depending on how sensitive a fish species is, even the slightest change in required water parameters can cause your fish to develop stress. That’s why it’s always smart to keep a top-quality water-testing kit handy because it allows you to monitor a tank’s water conditions regularly.

Work on checking all the necessary criteria, such as water temperature, pH levels, oxygen levels, nitrate and nitrite levels, etc. Be sure to immediately fix whatever is off the mark to help your fish get back to normal. On the other hand, if everything turns out clear, you can move on to investigating another possible cause (listed below).

– Unsuitable Tank Mates

Another likely culprit behind fish anxiety is bullying. If you pair a shy species with a semi-aggressive or aggressive one, you’re asking for trouble. Besides that, fish can turn on each other due to lack of space. Even the most peaceful fish can turn moody if another species suddenly encroaches on its territory.

Bullying or unsuitability is pretty easy to spot because the fish will start behaving a little strangely. For instance, some fish take to hiding for long periods, while others pick fights. If you suspect your tank mates aren’t getting along, it’s best to remedy the situation as soon as possible by setting up another tank for the species you plan to shift.

– Swim Bladder Disorder

If you’re not aware of what swim bladder disease or disorder is, it’s a condition where your fish’s swim bladder doesn’t function the way it’s supposed to. Swim bladder disease can affect any species, but it’s more prevalent among Bettas and Goldfish.

The confusing part about this condition is that it can occur due to various factors. There’s a bit more to Swim Bladder Disorder that we can cover in this section. Don’t worry; there’s an entire heading devoted to discussing this health concern below.

Symptoms, Causes, and Treatment of Swim Bladder Disease

If you notice your fish swimming head down, it’s likely suffering from swim bladder disease. But, before we move on to discussing the other symptoms and possible causes of the condition, let’s focus on understanding the disease itself.

The swim bladder is an internal organ found in fish that helps them retain buoyancy. Simply put, this organ goes a long way in helping fish swim and float, which makes it a serious concern.

When a fish is diagnosed with this condition, it means something’s keeping the swim bladder from functioning at a hundred percent. That’s why fish with this condition will often exhibit buoyancy problems or irregular swimming patterns.

– Common Symptoms

Here are some of the signs of swim bladder disease besides swimming vertically:

  • Fish sinking to the bottom of the tank
  • Fish floating around the top of the tank
  • Fish floating on either side
  • Fish floating upside down (belly up)
  • Distended belly
  • Curved back
  • Inappetance
  • Inability to move at all

One of the reasons swim bladder disease is sometimes confused with pregnancy is that some symptoms are similar—for instance, growth in girth, lack of appetite, etc.

Thankfully, one easy way to differentiate between the two is to determine if your fish is mature enough to breed. Another protip is to try and sex the fish. If only males or females are in a single tank, you can rule out pregnancy.

– Possible Causes

Discussing possible reasons for swim bladder disease is vital because the cure will depend on the cause. Here’s what a few of them are:

  • Bacterial infections or parasites that are discovered late and have plenty of time to cause mayhem can end up affecting (or inflaming the swim bladder). That leads to pressure building on the organ and influences functionality.
  • Enlarged organs can also bear pressure on the swim bladder—for example, enlarged liver due to fatty deposits or kidney cysts. The development of eggs or fry in the female fish’s belly can also exert stress on the swim bladder and lead to buoyancy problems.
  • At times, the stress on the swim bladder results from an internal congenital disability, but in such cases, buoyancy concerns are present from birth.
  • Constipation and impaction can also create concerns with the swim bladder. If the fish can’t pass stools, the waste building up in the gastrointestinal tract ends up straining the swim bladder.

– Treatments

In the case of infections or parasites, treatment with antibiotics can help clear out the cause and fix the swim bladder concern.

On the flip side, if the pressure on the swim bladder is due to an enlarged intestine, the best thing to do is put your fish on a temporary fast of at least three days. At the same time, set the water temperature at 79 F and keep it stable for all three days.

The next day, grab some frozen peas and thaw them out. Next, boil the peas in water for less than half a minute, skin them, and feed it to your fish. For the next few days, continue feeding your fish a diet consisting of boiled peas until you notice your fish is swimming normally.

Other helpful treatments for swim bladder disease include:

  • Mix in a small amount of aquarium salt in the aquarium to eliminate parasites
  • Reduce the water level in the tank can help the fish swim better
  • Reduce water flow in the tank to reduce the amount of effort the fish has to exert to swim

Besides all the treatments mentioned above, you also have the option of contacting an aquatic veterinarian. A qualified vet will be able to get to the bottom of things and help your fish get better faster.

Nevertheless, it’s also important to remember that sometimes there is no cure to swim bladder disorder, in which case, the veterinarian may recommend euthanasia.


Fish swimming verticallyIf you notice your fish swimming vertically for extended periods, it’s best to observe them closely. A switch in swimming patterns may be indicative of a health concern. Here’s how fish keepers can tell if there’s something to worry about:

  • Your fish may be swimming vertically due to being pregnant. Some fish species swim vertically and go off their food when spawning draws near.
  • Stressed fish can take to swimming in a vertical fashion. Symptoms of stress in fish include odd swimming patterns (i.e., fish swimming nose down), rubbing on gravel or tank decorations, lack of appetite, etc.
  • Swim Bladder Disease can occur due to various reasons like bacterial infections, constipation, enlarged organs, etc.
  • Disease symptoms can include a distended belly, curved back, inappetence, lethargy, sinking to the bottom of the tank, among others.
  • Treatment of Swim Bladder Disorder will depend on the cause. For example, bacterial infections will require antibiotics. Nonetheless, the best course of action is to seek advice from an aquatic vet.

Unless you’re sure your fish is swimming vertically due to gravidity, it’s best not to take an abrupt switch in swimming patterns lightly. A quick trip to the aquatic vet will not only help your fish receiver faster, but it can also help put your mind at ease.

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