Something Growing In My New Aquarium?

Hey everyone, I am super new to aquariums. I have always had a fascination with fish and the other day we took my 14 month old daughter to the aquarium in SLC and she loved looking at the fish and following them in the water, so I felt it was time to get my own aquarium. I got really excited about having my own aquarium and fish so I jumped into it all rather quickly.

I currently have a 10 gallon tank that I got used from someone. I have just a betta fish in the tank right now as we might be moving somewhat soon and I dont want to add any other fish until we have somewhere more permanent.

I have had the fish in the tank for about 3 days now and last night I noticed my water was a little but more murky than when I first put it in and I needed these things that looked like almost underwater strands of cobwebs. I dont have a lid on my fish tank so my initial thought was well maybe this is dust getting in my water so I ordered a lid for my tank, it hasnt arrived yet. I then began to look into more details and so some research to see if anyone else was having the same issue with their tanks that didnt have lids on them (from what i found the answer is no.) So i started looking at what it might be and the closest thing I can find to it is maybe hair algae? Can a tank really grow algae or bacteria that quickly? I mean the fish has been in there for only 2 days now. I took the best possible photos I could so that you could see the white/clear strands in the water. I also have two marimo moss balls in the tank with the Betta so maybe that has something to do with it?

 

I’ve never seen anything like that in my tanks.

I would clean the plants and do a 50% WC just in case with dechlorinated water.