Yesterday I did my standard water change of 50% on my 75 gl. I wake up this morning to a tank full of fish, all gasping at the surface for air. Upon closer look I see three dead Dension barbs floating amongst the plants. I do a water test and see that I've got a reading for ammonia of 0.50. I immediately do a 75% water change. After the water change, I test for ammonia and see that I have a reading for 1.0.
I add an extra dose of Prime, test the water and then have a reading of 0.50. What the heck is happening? I don't understand this, as this tank has been set up for a month (stuffed full of plants) and a week ago after the last water change test results yielded a zero reading for ammonia and nitrites, and a 10ppm reading for nitrates.
I decide to check my tapwater for ammonia...it reads 1.0! How and why does this happen? I've tested my tap water before in the past and it's always tested a big fat zero for ammonia. I'm so bummed about losing three of my barbs. Any advice? Do I call the water company? What will I do in a week's time when it's time for water changes and my tapwater is still reading 1.0 for ammonia?
I suppose now I'll go outside and bury the three barbs under my rose bushes. No sense in wasting their bodies, today's dead fish will be next week's blooms.
Not to be morbid but here's a picture, all three fish look exactly the same, with their mouths wide open, color is totally grayed out on all fish, no body bloating. I can only assume ammonia poisoning caused their death?