Disease Identification Help Please

Hi Everyone

I need some help here please, not sure if this is actually a disease?

Disease
Describe the problem that the fish is having - Green\Blue mark on body, getting bigger
Is the fish eating? - Yes
Has the problem occurred before? - killed 1 other fish
Have you treated the problem and how? - Daily Water Changes, Rooibos Tea and a bit of Salt
Have you had any other problems in the past? No

Your aquarium & Maintenance
How big is the tank. (L x b x h)? - 2ft
How many litres of water? - 60L
What type of filter do you run? Seachem Tidal 35
What is IN the filter? Seachem Matrix, 2 x filter sponges
How many litres per hour is the filter rated for? - 500 l/h
How often do you clean your tank? - Weekly
How do you clean your tank? - Water Change, Vacuum of gravel, remove dead plants\snail shells
How much water do you take out for Water change?
Do you prepare your water for water changes? How and what do you add? - Aged Water, declored
What water do you use. (Tap, bore hole, RO)? - Tap
What substrate do you have? -
What else is in the tank (Rocks, plants, fake plants, shells, anything else)? Planter Tank

Water parameters in your aquarium
Describe the water (smell and colour)? Normal?
Temperature of the water? 22
Lights
What light do you have? Jebo
How long is the light on for? 12 Hours
Do you have lots of plants in the tank (real or fake)? Real
How do you fertilize the plants? Scap Complete, Scape NPK every few days

If possible, can you post some pictures of
(1) The sick fish
(2) A close up of the sick fish, and/or effected area - The weird green spot, so far only on 1 x Harlequin Rasbora, the Espei that had the white tail died or is hiding
(3) the full tank.

 

Looks like a cyst to me

 

Afraid not, got home today with 3 dead fish and 1 skeleton...

My other fish also got the same white mold this afternoon, water is a bit dirty because I bumbed the plug and the filter restarted

 

Thank you for the response, I have been reading up since the original post and cant quite figure out what it is, but I went to take more photos now and I can see its spread rapidly on the sickest of fish, with my cories seemingly unaffected from the looks of it and otots I have 1 left while shrimp population has been wiped out and this green tetra is struggling to swim. i Have been doing weekly Water changes and cleaning of filter, so not sure, but this article seems to describe the symptoms quite well, especially the loss of the fish colors

https://www.aquariadise.com/columnaris/

 

Woke up this morning and had another 2 dead fish...

When to LFP and could only find Sulfaplex, bought it cause i figured it should also help based on the website and dosed, hopefully it stems the tide