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Help identifying dark spots?

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Hi everyone!

I posted a little while ago about some dark spots I found around the walls of my tank towards the top of the water. I received some helpful advice that it could be some kind of algae, but noticed that it’s now on our decor.

I’ve checked the dots under a magnifying glass and they do not look like they have legs or seem to move. I can easily remove them from the tank walls with a silicone scraper, but I can’t seem to find any information to confirm what they could be and they seemed to spread pretty quickly. They’re all fairly uniformly sized and don’t seem to break apart at all when I remove them. 


Tank info:

5 gallon

1 betta

1 nerite snail


kept at 79 degrees

water is tested weekly

Ph 8.0

Ammonia: 0 ppm

Nitrite: 0 ppm

Nitrate: 5 ppm


Thanks everyone, I’d appreciate any help!




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Are there any snails in the tank? There is a chance that they are snail eggs. If not, there is  a good chance that it is some sort of pod, maybe from a bacteria or pests. Don’t quote me on that though.

We’re they there when you set up the tank? Have they changed size any since you first noticed them? Also, I do know that it is a bit of a long shot, but if you somehow have access to a microscope, put it under that and share a pic. It might help.

Besides me, there is a chance that @Streetwiseor @Guppysnail might know something that I don’t.


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They are not snail eggs of any type I’m familiar with. I’m not sure how long this tank has been set up. In my experience things grow in aquariums. 90% if not more are entirely harmless and completely natural. I rely on my fish to tell me if something is not ok. Fish will display some level of stress if there is something harmful living in their tank. I have learned to simply watch micro flora and microfauna as part of the maturation of ecosystems. If you have various micro fauna/flora growing it is a good sign. Your tank is alive and life is thriving. If it begins to cover completely/densely 25-50% then I may question that something is out of balance but still not harmful if fish are not distressed. I know not being able to give a name to what it is is not helpful to what you are seeking but hopefully my response can at least set your mind at ease a bit. 

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@Guppy Guy thanks so much for your input and I appreciate you tagging the others!


@Guppysnail They both seem healthy and unbothered, so that’s good news! We’ll continue keeping an eye on them. Our tank’s been cycled since April so we’ve had it for a bit now. But that’s a really good point, and thank you very much for passing that information along. It definitely puts my mind at ease! 

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