I have a small tank, about 4 gallons. This is a new tank, and the 1st photo is in its 2nd month, looking good.
But the 3rd month, the foreground plants is turning yellow, brown, and I guess it is going to be black.
No significant parameters changed. I didn't dose any fertilizer, and given this is a new tank, I don't believe it is due to lack of fertifizer.
Please help diagnosize and save my tank!