dying one by one

I have aquarium gravel, which I know isn't ideal, but I didn't think it could be problematic. Could it be the reason my cories are dying off? My water parameters check out fine, but I only have test strips. I'm getting a test kit later on today so then I'll know for sure if water quality is an...

There's two platies and two corydoras of different species. There used to be more than that and now I don't want to look in the tank. I used to have a school of corydoras, but they all died off one by one to parasites I guess if that can kill them a day/a few hours after showing symptoms. A...

This is extremely stressful. Now out of my three survivors, one is on the ground not moving again. I went on vacation so I couldn't monitor the water everyday. During the vacation, there was no food given, and lights off. Water parameters turned out fine according to the card that came with it...