Spotted a wiggly worm or parasite in one of my tanks, it was free swimming and fighting the current. Had no fear of being out in the light. It has a thicker part just below its head making it look like a long tailed sperm.. wtf is it? Its in a tank with a mostly blind betta so I don't know that he'd eat it (he can't rally see it). This thing is tiny, smaller and thinner than a full grown grindal worm.. I don't have a ruler on hand to estimate cm or mm of it.
Here's a mostly in focus shot of it, looks white in the water but tan/orange on a white plate (head is on right side in 1st photo, left in 2nd)
Some more info:
The betta gets fed Hikari betta pellets (going to switch to better quality pellet soon), (thawed) frozen blood worms and brine shrimp (sf bay brand) and yesterday started omega one frozen dalphnia in the diet.. first time I'd seen this thing in a tank. Tank is planted and has been set up for over a year. Nothing new added to the tank recently except a floating glass thermometer I picked up at the store yesterday (as sealed in packaging). 2 days ago i removed dead java fern leaves during a water change other wise tank has been left alone.
Any help IDing it would be appreciated