[swordtailbreedr]

Yesterday I did a 50 percent water change on my 29g with 6 neons in it. Lucklielly it wasnt all my tanks as i ran out of time!! After the water change I came back and 5 neons were dead and one looked stiff and it would like spasm somtimes.I wanted to save it so i transfered to a new tank.then it swam to the top and died

My question is why would have caused this?

I used prime on my tap water