Tiny white worms. Planaria or harmless?

[Karen B.]

I have tiny white worms on my aquarium glass. They aren’t long and wiggly like detritus worms. But from what I can see, they do not seem to have the triangular head shape of planarias... any idea what these are exactly? Thank you!

 

[darkG]

Some flatworm or other, people use to say Rhabdocoela but in my feeble attempts to teach myself I shot for Catenulida. They are not likely to grow much bigger and are not parasitic, so no worries, I'd say. (Mine were somewhat predatory, but they are small.)

[JohnT]

These appeared recently on my cichlid tank. I was freaked out at first but later found that 1) they usually are harmless and 2) they are fish food! Some people recommended using Hydrogen Peroxide to get rid of them, however I think that will also kill beneficial bacteria in the tank so I actually didn't do anything besides vacuuming and changing water more often for a week and a half may be.

[Gloryview Farm]

Not sure what (who) you have in the tank right now, but when these showed up in my shrimp tank I panicked, and then after resuming normality, I put two of my guppies in the tank for a special spa vacation.  you should have seen them go after these little buggers!!  of course it helped that I had not fed them for two days (trying to clean up the algea in their tank).  and in two days every little white thing-a-ma-bob was gone!  and I had two very fat and happy guppies to send back to their home.  good luck with them, I know that even if they are harmless, I hate seeing them in the tank.

 

[Trish]

1 hour ago, JohnT said:

These appeared recently on my cichlid tank. I was freaked out at first but later found that 1) they usually are harmless and 2) they are fish food! Some people recommended using Hydrogen Peroxide to get rid of them, however I think that will also kill beneficial bacteria in the tank so I actually didn't do anything besides vacuuming and changing water more often for a week and a half may be.

I bookmarked this Hydrogen Peroxide info taken directly from Marks Shrimp Tanks and recently tried it in my shrimp tank using his dose of 1.5ml per gallon.  I actually only used 1 ml because I tend to be cautious.  Another site Aquarium Breeder who is informative about keeping shrimp recommended it for killing Hydra.  While my tank didn't have noticeable Hydra it did indeed rejuvenate my Cherry Shrimp, they are much more lively, not hiding and eating better.  Mark speaks about the effect of hydrogen peroxide on beneficial bacteria, stressing that the right dose of peroxide must be used without overdosing and that if one turns off the filtration that the beneficial bacteria growing inside the filter will not be sacrificed.  Bio Film on the glass will be killed but he suggests it will grow back shortly.  

https://marksshrimptanks.com/2018/10/24/hydrogen-peroxide-in-the-shrimp-tank-game-changer/ 

https://aquariumbreeder.com/hydra-in-a-shrimp-tank-treatment/