I recently had to move my tank so i had to remove 60% of the water and replaced with new. I have a 20 gallon tank that was in pristine healthy condition for over a year, until i moved it. I replaced the water and added the appropriate amounts of chemicals and aquarium salt just like i do with every other sucessful water change. More than half my fish died abruptly and unexpectedly.
My community consisted of:
2 sm Clown Loaches (now dead)
2 sm Bala Sharks (now dead)
1 md Dalmation Molly (now dead)
1 sm pictus cat (now dead)
2 md Chinese Algae Eaters (remained healthy)
1 sm Tiretrack eel (4"-5") (remained healthy)
1 md Gold Veil Angel (remained healthy)
I have always fed a combo of frozen blood worms, algae wafers, flakes and granules (not at the same time of course.) After i changed the water i purchased a pleco and about three days later it died. Two days after my bala's developed a milky/faded look and eventually their eyes clouded up. They lost thier appetites then started swimming like they were sick and they died. I couldn't really tell if they had spots or not. The loaches followed suit but they developed small white specs first. The Algae eaters and Angel were not affected at all, no spots, discoloration, or odd behavior at all. The eel is ok too, but it's a bit faded. This all happened over about three days.
on the second day, i treated the tank with API's super ich cure. I followed the directions EXACTLY and even removed tha carbon for the treatment then replacing with new after 25% water change. It's been two weeks now and i bought some new fish to test:
1 sm loach
2 sm balas
1 mystery snail
1 rubber pleco
It's 4 days since i put those fish in and the eel ate the two Bala's :( THe pleco and snail seem healthy, but the loach has the tiny white spots now and is acting like he's about to die.
My tank stays at about 82-84 due to the hot weather here in texas (which is supposed to be too warm for ich) and i did the treatment like i was supposed to. I take good care of my tank, it's clean and well maintained so i don't understand what's killing only some of my fish. Most of my readings are high since the 60% water change. Could I have poisoned the tank with tap water?
Nitrate 60 mg/L
Nitrite 0 - .25 mg/L
Hardness 200 ppm
Alkalinity 300 ppm