just cleaned aquarium now all fish are swimming at top looking like they need air

Question
"just cleaned aquarium now all fish are swimming at top looking like they need air"
Tank has been set up for several months.  It needed a cleaning - having a party in a few days.  Very large tank 40 gallons maybe.   I have  a feeling I changed too much water.  What do I do now?


Answer
Hi Amy;

The fish are probably in shock and/or it's an ammonia spike from a disrupted system. You might have to just wait it out and hopefully they will all recover in the next day or so. If you didn't use water conditioner, go ahead and add a proper dose now. Add extra agitation in the form of bubbles from an air pump, or a second filter to move more water around if you have one. Too much new water can be just different enough in chemistry (hardness, pH) to cause shock. That's why smaller changes of no more than 25% are best.

If the bio-system of your tank has been overly disrupted by the cleaning it will cause an ammonia spike. When a tank is over cleaned the beneficial bacteria can be partly or even totally killed off. The beneficial bacteria controls ammonia in an established and stable system. Have the water tested for the level of ammonia. If it's elevated, make a 10% water change every day that it's up. Hopefully the partial changes will help alleviate the fishes' burning gills so they can breathe easier. I usually recommend larger changes of no more than 25% but the fish may also be in shock so any change can be stressful. The trouble is that we have to keep the water safe for them to survive in too. A smaller change on stressed fish for lowering ammonia is a bit of a compromise that could save their lives. Hopefully the ammonia is fine and you won't even have to do it.

I hope they feel better very soon...

At Your Service;
Chris Robbins