Tiny Critters In My Tank - What Are They?

[LDBartholow]

First, I have checked the sticky about "hitchhikers", but these things are too small to identify without a microscope, so maybe someone can help me.
 
My betta tank is close to 2 years old. It's a 5.5g. I've never had any issues with it. The tank is lightly planted in my office. To clarify, it is an office building, not a home office. I have not added new plants or anything to the tank recently. I have not changed my fish food. I haven't introduced anything new to the tank. We don't leave windows open, etc. I leave the lid off when I'm here, but a lid goes on when I'm not. I left some carrot for my snail last night, and came back to work today with this. Uneaten carrot with hundreds of tiny critters. What are they, are they harmful, and what might I be doing wrong? I test weekly with an API master kit. My numbers are always zero ammonia, nitrites, and by the end the week, usually about 20-30ppm of nitrate. These things are definitely living. I can see them darting everywhere. I'd appreciate your guidance! Thanks!
 

 
 

 

[PerryClem0842]

I have had the same situation occurring over the past two days, and their numbers have grown quite a bit although from what I can see they are fairly white and dart around a lot. Their general shape looks a little bit like so "  >-  " . I would also like to know what I am dealing with here and are they dangerous to the fish Like Bartholow I have not introduced anything new or different food e.c.t and have regular checks of the water quality ending up just about the same.

 

[taffia1]

Are you on about the tiny black spots or the transparent gloop. Are they not eggs?

Sorry just read your post properly they are darting about. Sounds like infusoria

As a side note infusoria is used and and added to aquariums to feed small fry. So don't worry about them your fish may even clean them up themselves. I would stop feeding for a couple of days and do a water change. Cutting back on light might also help but I've never had the problem (not really a problem as such anyway) so google how to get rid of it and you will get more detailed information

 

[LDBartholow]

I did do a small water change, and figured since they were congregating on the slice of carrot, I could bait them with some more vegetable matter and just remove them like you would snails. I just wanted to make sure they weren't harmful.