why does my rasbora stay at the bottom of the tank?

Why Does my Rasbora Stay at the Bottom of the Tank?

Rasboras are always a popular choice for aquarium lovers, due to their lively and social nature, and their general hardiness. They’re excellent options for beginners and experts alike, but, regardless of your experience, it’s important to understand their behaviour to give them the best possible care. If one of your rasboras is suddenly spending a lot of time at the bottom of the tank, this could signify something that needs your attention.

Rasboras can stay at the bottom of the tank due to swim bladder infections, ich, or spawning. This behaviour can also signify that your tank isn’t the best environment for your fish. Staying near the bottom of the tank may be a sign that you need to perform a water change or adjust the temperature.

The rest of this article will tell you everything you need to know about bottom-dwelling rasboras, so you can better understand what this behaviour means and how to address the different problems it can signify. Read on to learn more.

harlequin rasbora
Harlequin Rasbora.

Why Is My Rasbora Lying at the Bottom of the Tank?

Here are some reasons why your rasbora is lying at the bottom of the tank:

  • Your fish has a swim bladder infection. Fish have an organ called a swim bladder that controls their buoyancy and ability to swim properly. Unfortunately, swim bladder infections are common. If your fish is swimming strangely, upside down, or unable to swim to the top of the tank, they might be suffering from an infection.
  • Your rasbora could be suffering from ich or another illness. If your rasbora is frequenting the lower section of its tank, this can mean that your fish is sick and needs treatment as soon as possible.
  • The tank needs to be cleaned. A dirty tank can make your fish sick. This is why it’s important to make frequent partial water changes.
  • Temperature adjustments may need to be made. If your fish is too hot or too cold, it might spend less time being active and more time near the bottom.
  • An aggressive tank-mate has injured your fish. An injured fish might not be able to swim regularly.
  • Your rasbora is spawning. Some breeds of fish spend time near the bottom of the tank if they’re pregnant or about to lay eggs. If you’re concerned that this is the case, the following section covers common rasbora breeding practises.

Do Pregnant Rasboras Stay at the Bottom of the Tank?

Rasboras do not get pregnant. They lay unfertilised eggs. If your rasbora is spending a lot of time laying at the bottom of the tank or swimming very close to the substrate, this can signify they are about to lay their eggs, or they have laid them and are now eating them. However, you should always also rule out illness.

But how exactly can you tell if your rasbora is carrying eggs or not?

How To Tell if Your Rasbora Is Carrying Eggs.

Rasboras are not livebearers. This means that they are never technically pregnant. They lay eggs, which then get fertilised by the males after they have been laid. Here are some common signs to look out for that your danio is carrying roe:

  • Your rasbora is visibly more prominent than normal. Obesity in fish isn’t exactly a common thing. If you notice that your danio’s stomach appears to be bigger than usual, this can be a sign that she is carrying roe.
  • Your rasbora is female. While this may seem obvious, you must know whether or not your fish is female before making any judgments about pregnancy. This is crucial because if your rasbora is a male, it’s likely that your fish is ill rather than carrying roe. This can also signify the need for water adjustments.

When it comes to laying their eggs, rasboras are what is known as ‘egg scatterers’. The female will release a large number of eggs at random, many of which will land on the substrate. Rasboras show no parental care, so, if you see your rasbora spending a lot of time at the bottom of the tank, they are most likely eating the eggs, rather than protecting them.

Are Rasboras Bottom Dwellers?

Rasboras aren’t bottom dwellers. While they’re known to have the occasional algae snack, they’re not naturally bottom feeders and should be swimming around the entirety of the tank. Bottom-dwelling fish include loaches, corydoras, plecos (plecostomus), and others.

If your rasbora is spending a lot of time at the bottom of the tank, this is considered abnormal behaviour.

lambchop rasboras
Lambchop Rasboras.

Signs of Illness To Look Out For.

Unfortunately, a bottom-dwelling rasbora could be a sick one.

As previously discussed, rasboras aren’t natural bottom-dwellers like loaches and other common bottom-feeder species. If you’re convinced that your fish isn’t pregnant, it’s essential to check for symptoms of common fish illnesses.

Here are some illnesses and ailments you should check for:

  • Ich: Ich is one of the most common illnesses seen in freshwater fish. It’s a parasitic infection that causes white spots to appear on your fish.
  • Swim bladder infections: An infected swim bladder can affect your pet’s ability to swim properly.
  • Fin rot: Fin rot is relatively easy to diagnose. While this is more common in bettas and other fish with more elegant tails, mollies can still be prone to this.
  • Poisoning (contaminated water): Unfortunately, it’s all too easy to contaminate the water in your fish tank accidentally. If you use harsh soaps to clean your fish care supplies, the chemicals in the soap can transfer over to your tank. You should also have a designated bucket for water changes to protect your fish from cleaning solutions.
  • Chlorine sickness: It’s imperative to ensure that the water in your fish tank is dechlorinated. If you forget this step during cleaning and/or water changes, this can make your fish very sick.

In addition to bottom-dwelling behaviour, here are some signs of illness that you should look out for:

  • White spots (ich)
  • Slowed movements
  • Rotted fins
  • Your fish isn’t eating
  • Increased or decreased aggression (depending on the typical behaviour of the individual fish)

How To Treat Common Rasbora Illnesses.

If you think your fish is suffering from an illness, it’s crucial to treat your tank properly. One helpful solution is to carry out a partial water change. I would also test the water. I personally would carry out the water change even if the water parameters are showing as fine.

It is also a good idea to have a quarantine tank in case you need to remove a sick fish away from the group. I have written a helpful article on quarantine fish tanks which you can read here.

Do Rasboras Like To Hide?

Rasboras like to hide, like most fish. Rasboras are very playful and are more likely to be swimming all around the tank though. Hiding places allow your rasboras to feel safe while getting accustomed to a new tank. They can also serve as shelter, just in case some of the other tank members show aggression.

Don’t for get that rasboras are shoaling fish. They need to be kept in a group of at least 6. If you only have one or two rasboras in your tank, the chance are they will be feeling stressed. This could be the reason why they are lurking at the bottom of the tank or hiding out of sight.

If your fish stays close to the bottom to hide, this is probably nothing to worry about. It’s still a good idea to double-check for symptoms of pregnancy and illness for safety.

chilli rasbora
Chilli Rasbora.

Final Thoughts.

Rasboras are always a fishkeeping favourite because they’re relatively easy to care for. However, no fish is immune to ailments. If your rasbora is spending a lot of time near the substrate, this can mean illness, spawning, or an inadequate environment.

Hopefully, this article has helped you better understand rasboras, so you can analyse their behaviour and continue to keep your fish as happy and healthy as possible.

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