Help! What is this?

[mrtajhya]

Help!
My tank is being infested by these brown, branching algae or whatever it is. It attaches itself to leaves of other plants and grow crazy.
Most probably it came after I disturbed a small portion of my substrate 3 weeks ago.

 

[Sgooosh]

that is Staghorn Algae.
what are your water parameters? it will help knowing this because an imbalance in nitrates or something could cause the outbreak.
for now it is best to hand-remove the algae.
what fish do you have in the tank?

 

[mrtajhya]

The tank is cycled.
Ammonia 0
Nitrite 0
Nitrate 5 ppm
PH 7.4
I do not have test kit for phosphorus and potassium.
I had been adding phosphorus and potassium along with other fertilizer to help my ludwigia palustris.
Fishes in tank - guppies, mollies, tetras, otto

 

[Sgooosh]

The tank is cycled.
Ammonia 0
Nitrite 0
Nitrate 5 ppm
PH 7.4
I do not have test kit for phosphorus and potassium.
I had been adding phosphorus and potassium along with other fertilizer to help my ludwigia palustris.
Fishes in tank - guppies, mollies, tetras, otto

how big is the tank and how many of each fish do you have in there?

 

[mrtajhya]

The tank is 20gal long.
Guppies about 4
Mollies 3
Neon tetras 3
Rummy nose tetras 5
Otto 1
I have attached the picture of my tank
Its heavily planted

 

[mrtajhya]

For now I am changing 20% water every other day and haven’t added any macro and micro nutrients.
I have also manually removed the algae