HomeOcean LifeFish KeepingTroubleshooting › White Spots on Glass

White Spots Growing on Aquarium Glass

So, everything seemed to be going well, and then you noticed some unusual speckles growing on the inside of the glass and on some of the objects inside the tank?

For the most part, there may be nothing to worry about. But, it's important to determine what's causing the milky white specks and learn the best way to get rid of them.

Causes of Small White Spots in Fish Tanks

Most likely, you started seeing a few whitish dots appear on the tank glass?

Then, as time went by, more and more of them started spreading?

As the situation worsened, you started seeing the same spots on the aquarium ornaments, and even on the leaves of some plants?

Here's the thing:

Once you start adding livestock (e.g. fish, plants, corals), there will be other organisms that can live inside the same tank.

Hence, when you introduce new fish and plants you'll also be bringing in these extra microscopic inhabitants. But, to the untrained eye, it could take a few weeks for you to actually notice the 'unintended' beings living inside your aquarium.

The key to determining what is causing white spots on the tank glass will be their appearance (what they look like) and whether they can move (or not). Here is a list of the most common reasons.

Aquatic Snails (Limpets)

Limpets are tiny snails that sometimes look like hard shelled white spots on the inside of the aquarium glass. You may not think they're moving at all. But they use their strong muscular "foot" for movement.

By and large, the presence of small white limpets is not going to harm your aquarium ecosystem. In fact, they eat fish waste and plant remains (not live plants), so they can also help aquarists maintain good water conditions.

Getting Rid of Limpets

Despite being generally harmless, most aquarists want to get rid of aquatic snails because they tend to make the glass look speckled. You can try scrubbing them away with a stiff sponge when you clean the glass. But, the hard outer shell makes them difficult to remove.

Snail Eggs

Are you seeing white spots grouped in small clusters or pockets? If so, you're probably looking at snail eggs, such as from the ramshorn snail or other parasite snails.

There is good news and bad news. Because snails eat fish waste they can help to keep the aquarium clean. But, they tend to produce a lot of waste products themselves (poop) and some species will eat any live plants that are growing inside the tank.

These species of aquatic snails tend to lay their tiny white eggs on the inside of the aquarium glass and sometimes in the semi-dry area at the top of the waterline.

How to Remove Snail Eggs?

If you already have snail eggs growing inside your setup, they will be difficult to get rid of because they multiply so fast. But, you can remove the eggs from plants and decorations by scraping them away to try and keep the issue under control.

Nerite Snail Eggs

Unless you have at least one female Nerite snail in your aquarium, the white spots that you can see on the glass or decorations will not be Nerite snail eggs.

Nerite snail eggs are hard and they'll be most noticeable against a dark background, such as hang on back (HOB) filter systems.

Scraping Off Nerite Snail Eggs

You can scrape eggs away from the glass and accessories. Even so, the likelihood of having a population explosion is very low. The main reason is that even if Nerite snail eggs hatch, the tiny larvae will not survive in a freshwater aquarium.

Freshwater Hydrozoans (Hydra)

In the main, you will be able to identify hydras by the way they stick to the glass. Take a close look and you might see a tube-like mouth and a ring of tentacles.

It's also fair to say that if you are seeing white spots in your aquarium, freshwater hydrozoans (hydra) will be one of the worst outcomes.

How to Get Rid of Hydra?

Aquarists consider the hydra as being a dangerous predatory organism to have inside a fish tank because they will kill and eat fish fry and shrimp fry.

There are several ways to reduce the numbers without too much difficulty. Many of the popular tropical fish species such as Gouramis and Mollies (as well as some large snails) eat hydrozoans.

Water Fleas (Daphnia)

These tiny organisms are a good source of food for most fish species. So, if you are feeding daphnia to your stock, and you see tiny white speckles darting around the tank, you may not have a problem at all.

Daphnia can swim. So, you may not see them stick to the glass at all. That's how you can differentiate them from limpets and snail eggs, for example.

Pro Tip: In general, there's no need to remove daphnia and other harmless worms from your aquarium because this kind of live fish food can help you keep the tank clean.

Divers also enjoyed reading about...