White live strings

[newbie hob]

last night when i got back home from work i found White live strings (worm like) occuping my entire 8 gallon grow out tank, they where swiming all over the place, the water readings was only high on nitrat .30.

i ended up striping the whole tank, sanitizing everything and rearanging my entire setup of tanks.

What are those strings??? what could have caused it?? is there a possibility that i might have transfered some of this to my main tank while switching the fish. striping the small tank is one thing but the main tank is another , i did make a 50% water change on the main tank right after finishing the sanitation of everything i got

 

[newbie hob]

doing a little further research i think they might be planaria ( if im not mistaken), i guess i over panicked, i think

 

[newbie hob]

well i lost more than half of my grow out tank due to my haste decision and rushing into things ive been raising and pampering my fry for the past couple of months to loose most of them in a couple of hours