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Daphnia visitors

 
   >From: "Tomoko Schum >I am puzzled about the strange visitors in my
>daphnia container.  There are some worms that look
>a bit like grindal worms and small water bugs of
>some sort swimming in my container of daphnia
>pulex.  

I would guess first that they are a type of Naid worm (assuming you are in N. America) and Cyclops. They may have been transferred with the snail not by the snail since both of these small critters often live in aquariums. We fail to see them because the fish see them first and keep the population low but not zero. Naids are the commonest North American freshwater worm and an important part in the diet of a number of native fish fry. They tend to hang at the surface with their head and tail in the water and their body looped above it. Swimming motions are whiplike but the head of the worm follows a straight line while the entire body goes through whiplike undulations. Cyclops is a tiny crustacean that feeds on detritus and algal mats. It tends to collect in upper corners of its container. Looked at very closely it resembles a tiny tadpole. Some have two "tails". I have raised a pink version of naid. They come in many colors including clear, white, & yellow. They are harmless, but be sure you have this worm and not some parasitic worm. If you magnify them, you will see it is related to the earthworm, segmented, with hairy pads. It reproduces by a varient of budding. A worm develops a new head and tail in the middle and then breaks apart to form two shorter individuals. A long chain of individuals may form before being broken apart. Cyclops are great fish food if you are very careful in feeding them. They can bite back, so don't overfeed. Don't feed them to any fry with any vestage of a yolk left and be careful not to introduce them anywhere you might be having fish eggs laid. They will take over a Daphnia culture. I just dumped out a 100 gallon culture because it had Cyclops. My wife can tell they are there without looking because she smells them. She can't stand their smell so I never culture more than a ten gallon tank of them.


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