PLease can someone help......My fish are all starting to die. I posted the other day when one of my oscars died and then this morning my Tandanus catfish died(which is an australian native) now my salmon cat is lookin sad and my other oscar is a bit off color..I have checked the water and the only thing that is showin not right was the ph was down a little..have dne whats needed there but what else can i do i dont want to loose them all when the oscar died she most deffinitely looked like she had hole in the head but these others are just hanging low or high then dyiing PLEASE HELP>>>>>>>>>> 
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