I went to sleep in my grandma's house and when i came back the ph of my aquarium was very very acidic, my Oscar is laid down, i treated the ph but he is still laid down, i don't know what to do now, please help
Do a 50% water change and gravel clean the substrate every day for a week.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
Add a couple of shells or small pieces of limestone rock to the tank to help stabilise the pH. Monitor the pH over a week and if the pH keeps dropping, add a bit more limestone. Continue adding limestone or shells until the pH stabilises and doesn't drop over a week.