White Spots on Fish Tank Glass: Causes and Solutions

It is almost always surprising to notice white spots on aquarium glass, woody objects inside and even on the decorations inside a fish tank. You may find few spots to detect early on, but the numbers keep increasing with time.

However, there is nothing to stress about in such cases. The spots are not imperishable and can easily be eliminated with some simple approaches.

This article will provide you with a thorough inspection of your fish tank’s white spots with simple solutions to eliminate them completely.

White Spots on Fish Tank Glass

What Causes the White Spots in My Fish Tank Glass?

There can be a number of reasons behind the appearance of the spots. The spots, nevertheless, render the fish tank unattractive and may cause harm to the aquatic species roaming inside the tank.

Aquatic Organisms

In reality, a lot of different organisms other than the desired ones may dwell inside a fish tank/aquarium. It may take weeks or months before you notice these additional occupants.

The fishes and plants attract other living beings like plankton, algae, limpets, daphnia, hydra or a myriad of other aquatic species.

The white dots that are troubling you are very likely to be some small living creatures hanging on the glass. On the basis of their movement, they can either be small life form or their eggs.

Rigid White Spots by Limpets

Rigid white dots can be formed by the presence of tiny snail eggs or limpets. They are not likely to move and build hard white spots on tank glass.

However, they are harmless for the living fishes in the aquarium. Yet, an increase in these spots will make the aquarium less attractive.

Smooth, Sloppy White Dots

Smooth and sloppy white dots are produced by the eggs of the parasitic snail. These spots are marked by tiny eggs grouped in pockets.

These can rapidly multiply and invade the aquarium if you do not take action right away. Additionally, the wastes generated by these pests influence the water quality which may disturb the fish.

Hydra Infestation

Sea Anemones and Hydra are related, and both species catch food in very similar ways. They often live in tiny colonies and divide for their reproduction.

When catching prey, hydras employ what seem to be tiny hairs arranged in a star pattern; their colors range from white to green.

These tiny hairs may pierce a fish’s scales if they are small enough and contain a numbing poison. Hydra infestation should strictly be eradicated in a fish tank.

Moving Spots in Glass

There are lots of tiny creatures which appear as little dots in a glass. These spots are characterized by certain motions and perhaps caused by daphnia or small helminths like worms.

Their presence might sound unpleasant but in reality, they are an essential constituent of the fish tank ecosystem. So, unless they have any visible harmful effects, these smaller organisms should not be eradicated outright.

How To Get Rid of White Spots on Fish Tank Glass?

If you investigate the spots maybe through a magnifying glass, you will surely be able to determine the culprit causing them. This will help you to clear them out of your fish tank.

  • The rigid white spots can be removed by scrubbing them with sponge. This may take a laborious effort but you will get flawless glasses without the spots as you clean them thoroughly.
  • Smaller soft cohort of spots can similarly be wiped out by scrubbing but an exception is that you might need to clean the tank frequently since these snail eggs are produced rapidly. A permanent solution is to clean the tank outright and a complete change in water if possible.
  • It is frustrating to get rid of hydra. There are a few typical approaches: Purchase a blue (or three-spot) gourami first; they appear to enjoy these small creatures.
  • Alternately, take out every fish and subsequently increase the temperature to around 105 degrees Celsius and add 4 teaspoons of salt for a gallon of water. But the latter process can be harmful to the plants in the tank.
  • However, some aquatic organisms are essential for the fishes as they help reducing waste and provide some symbiotic benefits for the desired organisms inside.

How To Remove the Lime Spots from The Aquarium Glass Safely?

Since the lime structures look awful, there may be a strong desire to utilize household cleaning supplies like detergents upon the spots to get rid of them.

But the tiniest amount or trace of these products may prove toxic to the fish and can substantially damage the aquatic population in the tank. You should not use these chemicals even at the steep edges of the tank.

Products are designed and available for the safe removal of lime from aquarium glasses. You can look into your neighborhood pet store to find sprays to clean up the glass.

If you’re looking for solutions available in your home, you can try applying vinegar after drying the tank. Vinegar is an inexpensive natural acidic agent that dissolves the lime without harming the life inside the aquarium.

A simplified process to clean up this stubborn limescale is provided below:

  ● Transfer the fish from your aquarium to a holding tank.

  ● Once the fish are completely relocated, remove all the water from the tank.

  ● Remove the plants and decorating structures as well

  ● Dry the tank or soak the water up using a towel.

  ● Apply a sufficient volume of the vinegar upon the affected glass surface.

  ● After that, leave it for 15-20 minutes.

  ● Now scrub the glass surface with soft materials like cloth

  ● As cleaning is done by now, rinse the tank with water before depositing water again.

Perform all the steps carefully to avoid damaging the glass or the glue holding the glasses together.


How Do I Prevent the Formation of This Lime?

If you are not likely to take the hassles of a laborious scrubbing you should prevent lime formation. Check the water supply line to your fish tank routinely since evaporation is the major reason behind mineral accumulation.

Warmer days will enhance the evaporation rate and low humidity in winter will increase evaporation as well.

As water evaporates, the mineral concentration in tank water gets increased towards a higher lime density. In such a case, you should try using distilled water since all the mineral contents are removed in distilled water.

But this may be a bit costly and not applicable for fishes that require additional minerals in the feed.

You can check the water quality routinely. Inspection of the pH, alkalinity, and hardness of the water will give you a view of when to change the water and reduce the chances of possible lime accumulation on the glass.

This will also help keep a sound water environment for the healthy living of the fish.



Excellent water quality is necessary for the fish living in a tank. Hence, the fish tank should frequently be a subject of inspection regardless of identifying any spots.

Cautious measures should be taken when dealing with the spots since the glass materials can often cause accidents. Look out for steep edges when cleaning the tank.

On the other hand, some small crustacean species appearing like spots on the glass are actually beneficial for your fish. If you ever forget or cease to feed your fish, they will survive a few days consuming these little organisms.

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Arif H Fahim

Welcome to PetFishTank! My name is Arif. I make an effort to publish educational articles using my many years of expertise as a fish owner.

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