It's probably just hydra or planaria. Once you start your water changes, they should disappear.
How did you do the fishless cycle? Did you use ammonia or something else? Did you keep the same substrate from before? (You rarely see things like this in tanks without waste...)
Once you do get your fish, feed minimal amounts until the tank is well established.
Minimizing waste will also aid in removing the hydra or planaria...
How did you do the fishless cycle? Did you use ammonia or something else? Did you keep the same substrate from before? (You rarely see things like this in tanks without waste...)
Once you do get your fish, feed minimal amounts until the tank is well established.
Minimizing waste will also aid in removing the hydra or planaria...