New Tank Owner - Fish Dying

Hi Fuzzydonna 

I'm afraid I have some bad news for you.
10 litres is a very small tank and, despite what the manufacturers say, it is not suitable for any fish. Mollies in particular are big fish - females can grow to 6 inches long.

But for now you need to keep the remaining fish alive until you decide what to do.
When you say the nitrogen level is high, do you mean nitrate? And what are the levels of ammonia and nitrite?

The way to get any of the three down is by water changes, and I would do more than 20% every other day - I would do at least 50% every day. And if you have readings of ammonia and/or nitrite over 0.25 ppm, you need to do enough water changes to get them below that figure and keep them there. Maybe even multiple daily water changes. As long as the new water is dechlorinated and warmed to approximately the same temperature as the tank, the fish shouldn't suffer.
And I'm afraid to say that I do not know of anything you can add to the tank that will lower nitrate except perhaps a lot of live plants.




In the longer term, I would give serious thought to the tank. You really have just two choices. Either get a bigger tank - and for mollies this needs to be at least 30 inches (75 cm) long - or rehome the fish and get shrimps. 10 litres is too small for even a single betta (siamese fighting fish)


I'm sorry to be the bearer of bad news.

One last point - don't believe anything a shop tells you until you have researched it for yourself. Some (particularly large chain pets stores that sell fish) don't train their staff in anything but selling techniques. Others will say anything to make a sale. The health of the fish is low in their priorities.

Thanks for all the information i wish i read these forums before listening to the pet shop.
Yes the nitrate level is over 3.3mg
I am going to do another change today shall i do a test afterwards?

It is Nitrite i apologise going to change the water now and see what happens when i test

@Fuzzydonna it has just occurred to me to ask about the tank's filter. What is inside the the filter, that is what is the media like? Sponge, cartridge?  Or does it even have media or does it use the gravel on the bottom as the medium?

What make & model of filter do you have?

One on the most awesome things I learned very quickly when I started to use this forum was not to change cartridges when the manufacturer suggests. I have some superfish internal filters in some of my tanks, and these have cartridges which click into the filter housing. The manufacturer suggestes to change the cartridges monthly. If you do this you are removing all the beneficial bacterial that you have grown in your filter and replacing it with a brand new (uncycled) filter cartridge.

My cartridges mainly have sponge, which I take out and gently rinse in a bucket of tank water during the weekly maintenance. I then put the sponge back into the cartridge and click it back into place. This keeps all of your beneficial bacteria. I have some filetr media that I have had for around 12 months, and it is still working well, and giving very good water parameters (0 ammoni and 0 nitrite). 

As a beneficial side effect this also saves a fortune in new cartridge costs, as well as ensuring that you keep your bacteria.

Those cartridges are terrible. Sorry 

Zeolite absorbs ammonia and then it gets full and stops working. While they are working, ammonia stays nice and low but because the zeolite is removing the ammonia no bacteria grow. Then the zeolite gets full, ammonia is not removed but there are no bacteria to eat it so the level in the water shoots up. This is why they want to you to change the cartridges every month, to replace the zeolite before it gets full. But in your case you have rather a heavy fish load so the zeolite will get full quickly. You must have, or at least had, ammonia in your water because you have nitrite, and nitrite is made from ammonia.

The best thing you can do is to take out a cartridge, make a slit in the outer casing and remove the contents. Then put some sponge inside the casing. You can buy filter sponges quite cheaply, just cut it into slivers to make them fit. If there is more than one cartridge, do one now then the next in a couple of weeks till they are all done. This way you do keep the bacteria in the outer casing.



What is the highest level with the nitrite tester you are using? Is it 3.3?
When the level gets to higher than the highest colour of the tester it will still show as that colour. So if your tester goes up to 3.3 and you had 10 ppm it would still read as 3.3.
You need to do another water change, as large as possible leaving the fish covered with water. Test again after half an hour and if it still above 0.25 do another water change. And another water change if the reading is still over 0.25. You need to do as many water changes as it takes to get that level down.
And maybe the same tomorrow, and the day after and the day after depending on how fast nitrite goes up.

I should have added that if you do fill the cartridges with sponge, just squeeze them in water that you take out of the tank during a water change to clean them. There will not be any need to replace them.