Black Phantom Tetra

[Mc96928]

I have recently lost a whole lot of fish in my newest set up of a 20 gallon long freshwater tank.
I have lost 2 black phantom females
3 blood fin tetras
and well over 5 zebra danio.
I had added an air stone after i had a huge algae bloom
Most fish died without much of any signs
The most recent fish to die was my female black tetra
I saw 3 small fuzzy dots fight along the side of the body right behind the fin
I went to my lfs for their opinion and the guy said it sounded like a fungal infection.
He gave me Melafix and Pimafix but after looking at her, her mouth looked stuck in a open lock O. Later that day after starting treatment the neck seemed to split from the mouth leaving a gaping hole.
I woke this morning to find her dead and attached to the filter
Does this sound like a fungal infection? or a parasite? or something completely different.
I have attached a photo

 

[Fishfur]

Don't see a photo. Does not sound like fungus, sounds more like some type of parasite. Fungi don't move, parasites do. Some sort of worm or fluke, possibly.

 

[Mc96928]

The part that looks like the mouth. Is actually the neck that split.