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Freshwater Aquarium/What's in my tank?!?


Squirming thing
Squirming thing  

Squirming thing
Squirming thing  
Tonight I was zooming in on my tank and I see these things dancing around there like little naked palm trees with its branches squirming around on my rocks plants and glass. There's at least 50 of them. I attached an image. I'd really like to know what the name of this organism is and is it harmful to my fresh water fish in my 10 gallon tank?

Hi Alexandra

These are harmless nematodes that are feeding on excess waste. They come out more at night and many fish like to eat them, which is actually healthy for the fish. The nematodes themselves are not harmful to your fish, but the reason that they are in your tank is very harmful...overfeeding.

They can't be killed with chemicals. It would do more harm than good if you kill them anyway....besides excess waste already present, now would be these dead bodies decaying in there causing more pollution. The best way to get rid of them is to starve them by cleaning the gravel and cutting back on how much food you feed your fish.

Cut back your feeding to about 50%. Don't feed your fish more than they can eat in 2 - 3 minutes. Next, do regular water changes and make sure you siphon the gravel thoroughly. Until they are no longer present, I would do a 30% water change on the weekend, and another 10% water change about mid-week.

Hope this helps, good luck!


Freshwater Aquarium

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Richard Hight


I own and maintain several freshwater aquariums from 2 to 180 gallon. I can answer most questions about freshwater aquariums, including setup, cycling, maintenance, compatible tank mates, feeding. Moving? I've moved fish both across town and across the country and can help you get your little aquatic friends to their new home safely. I know and have experience with most freshwater community fish, South American Cichlids and African Cichlids. I don't answer questions about Goldfish or keeping Goldfish with Tropical Fish. I also don't answer questions about keeping crustaceans (shrimp, snails, crabs etc) with Tropical Fish, nor questions about saltwater fish or aquariums. I'm not available to answer questions on weekends, this is when I do maintenance on my own tanks.


Many years of personal experience with community tank fish, semi-aggressive fish (Barbs, Tetras, etc), Angels, South American Cichlids and African Cichlids.

HSG 2010-2011 prof

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