All Fish Died

Question
I had 5 small Tiger Barb and 1 clown pleco fish. Today when I came home from work, I found 2 of the Tiger Barbs dead. Later in the evening another 2 had died and so had Clown Pleco. They were all fine earlier. I'm not sure what could have happened so quickly. Nothing but food had been added to the tank. We had cleaned and redecorated the tank about a month ago and thats when we got the Tiger Barbs. We had Clown Pleco for a couple of years. We thought they were doing well and were going to add a few more fish. Now I'm not sure what to do.

Answer
Hi Sharon;

It may have been the cleaning four weeks ago. Right now is the time that nitrites would be elevated if it was cleaned out really well. Doing a serious cleaning like that can cause the tank to go through a break-in period all over again. It can really stress the fish due to high levels of "New Tank Syndrome" toxins. If you could let me know what size tank it is, what kind of filtration, what the water temperature is, etc., I can tell you how to proceed. Also, did the fish have any signs of obvious illness such as spots, patches, labored breathing, "sucking air" at the top of the tank, hiding more than usual, spitting out food, etc.?

All tanks need regular partial water changes to keep water chemistry consistent, the fish healthy and stable and maintain the biological balance of the tank itself. Replace 25% of the water once a week and vacuum the gravel every 2 to 4 weeks. It's a good regimen to follow for long term health of your fish.

At Your Service;
Chris Robbins