

Please help oh my god
I don’t know what happened. My parents were in charge of my fish tank while I was gone. I’m freaking out. I don’t know what could have happened. All the fish are infected with whatever the angelfish has. Red algae has spiked. There is waste everywhere. I’m in tears. How do I fix this. I just got home. I want to dose with kanaplex but I have a snail in there.
MORE INFO:
Long established tank, bubbler provided, water last changed a week ago (50%)