Urgent help with my Tetras tank!
Female black skirt tetra.
Today I have noticed that she has a black and red growth on the side of her jaw. At first I thought she had broken her jaw but she can eat fine and it doesn't prohibit her moment as all. She is also acting strange, normally she is very passive and calm but now she is jumpy and skittish, she even goes so far to ram against the glass when something just as simple as moved close to the tank this it is completely against her normally behaviour.
Ammonia is low, temp is 28*C and PH is 7.
The tank is 40 litters and and has been set up for just over 2 years.
I don't know the number of the filtration system but it is a blue planet four compartment filtration system.
I have 16 individual tetras, Five head and tail light tetras 2cm long. Three glowlight tetras 2-3cms long. Two black neon tetras 3cm long. Two red eyed tetras 5cm long. Two Congo tetras 5cm long. Two black widow tetras 4cm long. And one female bristle nose cat fish 4cm long.
Last week I did a water change and gravel vaccume and I changed 50% of the water and replaced it with neutral treated water. I change ulcer age between 50% and 25% water on a biweekly basis.
I have had my Black skirt tetras for two years.
I added a new natural wood cave that I brought from the pet store.
I use Aqua one tropical freshwater fish food.