I went out this afternoon leaving my lights on. It started raining in the evening and my windows were left semi open. After I reached home, to my astonishment, i saw 20 over flies (attracted by my light) inside my tank!
All of them were floating on the surface of my tank, i quickly tried removing them by using a small container. Some of them are still alive!
Did a 20% water change. However, my true perc is behaving weirdly now. Swimming aimlessly. Normally, by this hour he'll swim around the skimmer preparing to sleep. However, I bought a new true perc to pair up with him today, and pasted a black film at the back of my tank as well.
Anyone encountered this before? No idea is it because of the contamination of the flies or is it because of the new things i introduced today.