What Are the White Spots on the Aquarium Glass, Wood or Decorations?

I was very surprised when I started seeing some white spots on my tank’s glass: just a few early on, then more and more. The same spots can be seen on decorations or the wood inside my aquarium, and even on the leaves.

Which brought me to the burning question in the title, that I am repeating below:

What are those white spots in my aquarium?

There are actually many, many things that live in an aquarium, especially if you already have some livestock inside. Fish and especially plants will bring in these additional inhabitants and it could take weeks or months to realize that they’re actually there!

The white specks that you can see on your tank’s glass are most likely some living beings – or about to become some depending on the case. This means that they’re probably snail eggs or limpets (tiny snails).

It depends on how they actually look like and whether they move or not. Below, we’ll look at all the possible options, so read on!

1. Hard white spots in aquarium: limpets

In my case, this is what the white spots were: limpets. These are actually some tiny snails that appear as hard shelled white spots on the aquarium grass.

They seem not to move at all (although they do move, albeit very slow).

These little fellows are harmless but most people dislike them because they make the glass look bad. Your only option is to scrub them away with a sponge when cleaning the aquarium, but they’re pretty hard shelled and difficult to get rid of.

Most likely, if you have them, you won’t be able to completely get rid of them: because of their small size, there will always be one or a dozen left in areas you can’t reach or see. But as I said, they are harmless!

2. Soft white spots in groups: snail eggs

If the white spots are grouped in pockets, then we’re talking about parasite snail eggs. They could be something like the ramshorn snail or other type of the so-called parasite snails.

Ramshorn snail eggs (zoomed in)

These multiply like crazy and it’s very difficult to get rid of them if you don’t take action early. And if you’re already seeing their eggs as white specks on glass, plants or decorations… things won’t be easy.

The only options you have is to keep removing them and cleaning the eggs when you see them and at least keep them under control.

The problem with these pest snails is that they’re poop factories (influencing the quality of your water) and they could also eat some of your plants in the aquarium.

They are not completely bad, though: they are useful for eating waste and keeping the aquarium clean. But they multiply like crazy so it’s best to at least remove them by hand when you do water changes in order to keep the numbers under control.

Alternately, there are snail eating snails (the Assassin Snail) or snail-eating fish like the Clown Louch or Gourami. The problem with both the Assassin Snail and all snail-eating fish is that they will also eat snails that you want to keep in your tank (like nerites).

3. Hard white spots: nerite snail eggs

Mentioning the Nerite snails brings us to another possible answer to identifying your white spots on the aquarium’s glass: Nerite snail eggs.

These won’t pop up that often and the good news is that they won’t hatch, so chances of you having a population explosion are limited.

The Nerite eggs can appear as white spots on the glass (or anywhere in the aquarium) and they will eventually disappear. This is because the eggs will actually hatch, but the tiny larvae won’t survive in a freshwater aquarium.

Could be other types of eggs. Pictured above: Cory eggs.

Of course, the possibility of the white spots to be Nerite eggs is valid only if you already have at least one Nerite snail in your tank.

4. Moving white spots: daphnia

There are many tiny organisms that can look like small white spots and if they move, they’re probably something like daphnia or some sort of worms. These will be small and move fast, while not necessarily stick to the glass only (daphnia and other invertebrates swim!).

While having worms in your aquarium sounds unpleasant, the truth is that they are actually useful in most cases and most aquariums have them, even though you don’t always see them as they hide in the substrate.

As long as you have harmless worms or other invertebrates, you shouldn’t do anything to remove them as they actually help keep the tank clean (and provide extra food to your fish!)

5. Hydras

Now this is a thing that I fortunately never had to see live in my aquarium, but one that happens – and it lives up to the scary name it has.

Hydras will usually stick to your aquarium glass and it will be very easy to identify them because they have some tentacle like endings that float around from their back.

While interesting to look at, the Hydras can prove to be dangerous as they are a predatory and can kill and eat fish fry, shrimp fry, as well as smaller fish and shrimp. So definitely not something you really want to have around!

The good news is that Hydras can be removed from an aquarium if you have fish like Gouramies or even Mollies and even some larger snails can eat them (like the Pond Snail – but these multiply quickly, so be careful!)

Out of all the possible things – living or not living yet – that could be those white spots in your aquarium, the Hydra is probably the worst.


If you look closer (maybe use a magnifying glass to be sure) to the white specks on your aquarium’s glass, you will be able to identify what they are, based on the suggestions we made above.

As I said, in most cases, these things are not harmless (quite the opposite!) but they don’t really look good either, so people generally try to get rid of them. Unless it’s a Hydra, I wouldn’t though… they’re part of the ecosystem that we’re building!

And since you’ve got this problem solved, make sure you also check out my previous article on the best aquarium filter for your tank.

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3 thoughts on “What Are the White Spots on the Aquarium Glass, Wood or Decorations?”

  1. I have had my tank set up for 13 years and NEVER had these white spots before. This is the second time they have appeared in my tank. The first time they were noticed about a week later we had a baby catfish appear in out tank ( I have 2 catfish already). The spots were gone in less then a week. I have never had a snail in my tanks nor any new fish in the tank for over 2 years. So thinking it is not snail eggs. Any other ideas?

  2. I have 4 nerite snails and just noticed the hard white spots. Mainly on my filter and gravel filter when I took it out. The only possible mating in my aquarium is my angelfish and tetras. Which is probably not very successful with the size of my Pleco.


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