ok so i did a water change (btw all my fish were fine before this) and vaccumed my gravel did a ph test it was fine 7.2 & amonnia was the same every thing and there was no chlorine and i went to eat dinner and when i came back my dojo loach,my clown loach,my red tailed sharks,and my cory catfish all died within 10 minutes it wasnt chlorine i treated that with some liquid for fish i need to know what happened before i get new fish!!!!