Very High Nitrite Levels, Tetras Dying - Please Help

[jon246]

Hi,
I’ve recently moved house and have moved my fish to a smaller (60l) tank so I could set the big (120l) tank up, get it cycled, etc and move the fish back to that tank.

Since moving to the smaller tank about 8 days ago, three tetras have died; each on a different day.

The nitrite levels are through the roof. They were at 0.6 when the first tetra died. I’ve been doing a 30% water change each day and got the levels down to ~0.2, although a second tetra died during that period. Then I had to go away for two nights and when I got back today the nitrite was up to nearly 1.0 and I had a third dead tetra.

I’ve been keeping fish for four years so have some experience although I’m nothing like an expert – I’ve just followed the usual basic rules and never had any significant problems before. My gut feeling is that it’s as if the biological process in the filter is just not happening.

I just bought the 60l tank and it came as a package (Juwel) so the heater and pump/filter should be correctly sized for the tank volume.

I can’t test the ammonia, nitrate or hardness levels as the guy in the fish shop told me I should only worry about nitrite and pH

There were 11 tetras (mostly cardinals but a few neons) at first. Apart from seeming off their food, they don’t seem unwell – no visible injuries, swellings, odd behaviour, etc).

There are also four zebra danios, four clown loaches and a catfish that seem generally fine (difficult to tell as the clown loaches are always jumpy and the catfish spends all its time hidden.

Tank size: 60l (recently moved from a 120l)
pH: 7.0
ammonia: can’t measure
nitrite: gone from 0.2 to 1.0 in last 3 days!!
nitrate: can’t measure
kH: can’t measure
gH: can’t measure
tank temp: 28C

Fish Symptoms (include full description including lesion, color, location, fish behavior): Apart from seeming off their food, they don’t seem unwell – no visible injuries, swellings, odd behaviour, etc

Volume and Frequency of water changes: 25-40% most days

Chemical Additives or Media in your tank: none, charcoal pad in filter should(?) remove any unexpected impurities, I think?

Tank inhabitants: 11 (now 8) tetras, 4 danios, 4 loaches, 1 catfish

Recent additions to your tank (living or decoration): all new tank setup, washed well, no rock other than gravel substrate, one log, water de-chlorinator used as per manufacturers instructions.

Exposure to chemicals: none that I am aware of. I have not moved house far so the water hardness should be similar to before

Please, please can anybody offer any advice or suggestions? I have to go away again for 2 nights for work this week.

Many thanks in advance.
Jon

 

[Curiosity101]

Just out of interest why did you need to re-cycle the 120l if that's where they came from?

Also, cycled or not...double to water volume means half the toxin concentration....
Get them back in the 120l ASAP!!

PS. Clown loaches are FAAARR too big for a 120l...and are also very susceptible to chemical burns which they may get from those levels of Nitrite...this could lead way to all sorts of infections. And a loss of appetite is a sign of Nitrite poisoning.

 

[divegirl]

Awww hun....your tank is massively over-stocked!

You need to get a reading for ammonia and if I were you I'd do a massive water change ASAP.
Clown loaches need atleast 55 gallons, so will need re-homing in the long run.
But for now.....lots and lots of water changes!

Lisa x

 

[jon246]

Thanks for your replies so far Curiosity101 and divegirl.

Umm. I think I must have misidentified the loaches. They are about 2" long - not that large I thought?? They have about six orange and black bands along their bodies and a snout-like mouth.

I had to set up the new (60l) tank in my new home so that I could move the fish from the old (120l) tank in my old home. I'll get the bigger tank set up again ASAP.

Jon

 

[Curiosity101]

Nope you may have ID'd them correctly. But they're meant to grow to at least 12"-16" which is why they are far too big even for the 120l.

^^That's a clown loach.

 

[divegirl]

Can you post pics....they do sound like Clowns.....they start small, but have the potential to reach over a foot in lenght......

http/www.fishforums.net/index.php?showtopic=34953

I agree with Curiosity....get them back into the bigger tank and watch your stats. If you can't test for ammonia....keep up with daily water changes [as many as you can] until you can test.

Keep us posted.

Lisa x

Nope you may have ID'd them correctly. But they're meant to grow to at least 12"-16" which is why they are far too big even for the 120l.

^^That's a clown loach.

Will you stop posting at the same time as me!!!!!

 

[jon246]

Thanks again for all the advice so far. You are right – the fish are clown loaches, just relatively small ones. The place I bought them failed to point out how large they grow and the tank just said 2-4 inches.

I appreciate that the temporary tank is smaller than ideal for the fish I have but I really think that there is also some other factor that is causing the high nitrite levels. They were about 0.9 yesterday evening before I did a 40% water change, which should if my maths is right take the figure down to below 0.6. This morning, only 12 hours later, the nitrite is already over 1.0 (off the scale). Just measured the nitrite again and it’s back over 1.0 after only a further 12 hours.

I used to do a 25% water change in the 120l tank every two weeks and the nitrite reading was never over 0.1. So doubling the tank volume would not seem to me to be the only solution as this would at best only halve the nitrite concentration? Or am I missing something here with regard to the maths, dilutions, etc?

I’ve been using a biological additive that the LFS recommended. I’ve not relied on it 100% but thought it couldn’t hurt if the filter bacteria are not colonising properly.

Is there anything else that anybody can suggest I check to make sure I have covered all bases?

Many thanks in advance.
Jon

 

[Curiosity101]

The only reason Nitrite will be present is if the filter isn't fully cycled. By the sounds of it you are using a brand new filter and therefore it'll have had no bacteria on it. The bacteria convert the ammonia --> nitrite --> Nitrates.

In a cycled tank you have 0,0 ammonia and nitrites. And then do water changes every few days, every week or every couple of weeks to lower nitrates and generally refresh the water.

GET THEM IN THE 120L!!!
They will still produce as much waste, but it will increase in concentration slower so allow you to keep on top of it easier.

You are in a 'fish-in' cycling situation at the mo. Check out the 'New to the hobby' section 'beginners resource section' and reading the threads about cycling, and specifically fish in cycling.

PS. bottled bacteria products generally speaking are a waste of time and money.