dying

Question
I have 3 tanks all use same water(source) all fed same
all nearly same temp.  For some reason I loose fish here and there. Nothing noted just one today one next week one next month.
None are that old. Nothing exotic a few guppies a few mollies a few zebras. Today I lost a pleco. A week ago a zebra. Fish all seem pretty normal they get tetramin flake mostly and dried shrimp once or twice a week.

Answer
Hi John,
This will take some investigative work. The first thing I'd recommend is to test the water for these three levels - ammonia, nitrite, and nitrate. These levels should be as follows-
Ammonia- 0
Nitrite-0
Nitrate- under 15 ppm

Once we have the water quality factor cleared out of the way. We can progress further. Like did the fish exhibit any kind of odd behavior before they died? Have you changed anything in the tanks? Whether it be maintenance, water conditioner, new fish additions, ect.

My guess is that there must be something off with the water quality.

Let me know what you find out.

Hope this helps and good luck!
Susan~