Molly Fish Sinking

Question
Hello,
I have a 10 galloon tank for probably over a year now. My original fish gradually were dying. Im thinking because they were just getting old? Im not sure so I recently just bought three more fish, 2 black and white mollys, one orange fish (I dont know the name he was thin, had orange and blue on him, very pretty) and a tetra. I already had one tetra and my sucker fish left. Everything had been going very fine until I noticed my tank was getting very murky so I used this solution stuff to "clear up my tank". A couple days later I saw my orange fish dead at the bottom of the tank. Now usually when fish die dont they float? So I began to carefully observe my fish. Now I am noticing that one of my mollys who are normally very active and hungry stopped wanting to eat. I also noticed that he stays low to the bottom. Almost as if he is sinking to the bottom of the tank. I changed the water, and now he seems to be doing a little better, he eats when the food comes to the bottom. But still he wont go up to the top of the tank. Its almost like his body is to heavy for him to get up there, he does once in awhile go up to the top to what it seems like getting some air. Its like he wants to be active, because I see him and the other molly trying to almost play together, but its like he has the flu and just cant move around. Do you know maybe what is wrong with him? I dont know my exact levels. What do you suggest I do? THanks for your time!

Answer
Hi Amanda;

His swim bladder has failed. The swim bladder is an organ inside the fish that fills with blood gasses when the fish wants to float up in the water. When it fails it can't hold blood gasses anymore so the fish sits on the bottom. There are many possible causes to swim bladder failure. Stress, dirty water, temperature shock, and infection are just a few.

After adding so many fish at once to the tank, the beneficial bacteria that consumes waste toxins couldn't compensate for the additional waste load. This means toxins rose. That's why the water got cloudy. The stress from the toxins will cause problems in the fish like swim bladder failure so I think that's probably what happened. Make 25% water changes every 2 or 3 days until there is no sign of ammonia or nitrite. You can get test kits for them at your local fish store. Ammonia and nitrite will always be zero in a biologically stable tank. Water changes of 25%, sometimes daily, may be needed to lower them to a level the fish can tolerate until the system stabilizes. Don't drain all the water to lower them. The bacteria feed on these toxins and removing them only delays or stops the break-in. It will continue again and put the fish through even longer stress.

Test for nitrate too. (different from nitrIte) It is the final result of the biological process happening in your tank. Nitrate is okay to be up to 40 ppm. Regular weekly water changes of 25% are routine changes that keep it in check. That's the only effective way to keep it controlled and why water changes are so necessary.

There is no cure for a failed swim bladder. It has to heal itself and unfortunately it usually doesn't regain it's function again. He can still live a very long life in his condition though. It doesn't usually affect other bodily functions. Just give him places to hide if he gets bullied and even give him his own tank if needed.

Whenever adding fish to your tank in the future, just put in one or two a week. This gives the system time to grow more bacteria and compensate for the new increased waste load.

Hope he feels better soon......

At Your Service;
Chris Robbins