What's wrong with my tank?

[Maxkolbe]

Currently have a ten gallon tank with a betta, upside down cat, and an Otto.
I also have two live plants. Our water is hard and basic.
I recently started noticing a film on top of the water and a bunch of small white "lines" floating in the water.
It only started to appear after I got the betta. I also remember the betta had stuff like this in his cup. This makes me fairly certain that it came in with the betta.

What is this? Is it dangerous to fish? And what can I do to get rid of it? It may be hydra but I don't know what those look like.

 

[librarygirl]

These? Natural Aquariums - Hydra

Does the tank have a filter? Is it creating some surface agitation?

Can you get a pic of what it looks like, that might help identify it.

 

[Maxkolbe]

I have the filter that came with the tank (though I think it's clogged) and I am trying to keep surface agitation to a minimum since I have a betta. I am fighting an infestation of blue green algae /Cyanobacteria which has caused a film on top of the water. Now that I know what it looks like I am pretty sure that it is not hydra, no tentacles. Any other ideas on what it is?

 

[Maxkolbe]

These? Natural Aquariums - Hydra

Can you get a pic of what it looks like, that might help identify it.

I would but I don't think I could get the camera to focus on them. If it helps I would describe it as a bunch of dust motes floating in the water.