Please help if you can..!

[heroblobs]

Hi, I have been on this site many times now and have learnt a considerable amount in the short time I have been keeping fish, though I'm still no expert. I have a 55G tank with mixed species of Malawi fish. The tank has been running very well over the last 3-4 months and had cycled properly, all the tests I did looked ok. PH was 8.0, Ammonia, Nitrtite and Nitrate levels were low and the fish were "happy" up until about 10 days ago when I noticed one of my Auloncara juvenile had what I thought was swim bladder problems as he had definately lost his sense of balance. I did a 25% water change, removed the carbon bag in the external filter and applied some anti swim bladder medicine. I also removed the Zorb that came with the Rena XP filter, accidently mistaking it for carbon and it now seems in my haste to treat the 1 fish (which subsequently died), I have now had a further 3 fish die, 2 looking quite unwell and.....my pair of Convicts have spawned about 150 fry....
I think I may have overloaded the bacteria in the tank with the amount of swim bladder treatment that I used and I think the removal of the Zorb did nothing but speed the deterioration of the water as I'm pretty sure now that it assisted with keeping Nitrite levels down. I have put both the Zorb and the Carbon back and although the fish look slighly happier, the tank is far from the good water quality the fish had enjoyed up until this saga.
Can someone please recommend what I should do as it looks like I'm having to cycle the tank again but with the fish in it. I did a 50% water change yesterday and as part of the change, I'm adding Equilibrium salt as well as the obligatory water conditioner, but my question is: should I be doing 50% water changes daily until the cycle kicks in and Nitrites start coming down. Ammonia is not high at the moment but Nitrites are off the scale. Any other recomendations would be most gratefully received.

Many many thanks in advance.

 

[tstenback]

Keep up with the water changes. It will slow the cycle slightly but is necessary to keep the fish alive. Try to keep the nitrite level at 1 ppm or lower if you can. Keep us posted.

 

[heroblobs]

Thanks for the prompt reply.. I'll keep up with the daily water changes but what % should I do. Is 50% per day too much or okay.

Regards.

 

[tstenback]

Once the nitrites are down around 1 ppm you should be fine with 15-20 % daily. until then 50%. HTH

 

[semper fi]

if you have done a large water change of 50%, i would do smaller daily water changes. say 1-20%. you don't want to keep doing the larger changes otherwise you will crash the tank. you may have killed off a considerable amount of bacteria in the tank and it needs to reproduce to catch up.

you say that you have a malawi tank. are the convicts in the tank with them? convicts are not african, but new world. convicts are also very aggressive when spawning. are you sure that the fish had swim bladder and was not beat on by the convicts?

 

[heroblobs]

Yes, the convicts are in the same tank and were getting along quite nicely until the spawning occured. They have become quite aggresive now but my 1st fish died before the spawning occured. Though its fair to say that 2 other fish died around about the same time as the fry came along so I couldn't be sure exactly how these ones died. I initially thought it may have been to do with the convicts but just not sure because of this underlying problem I'm experiencing with nitrite. The nitrite test I did this morning read about 1.6mg/L. and thats after a 50% water change. I think I'll do daily changes of 20%.. When is the best time to get an accurate nitrite reading.? Presumably 24hrs or so after the water change.?

 

[heroblobs]

Apologies for my ignorance.... Great site btw, its been a wealth of information recently..

 

[tstenback]

you can check the levels of nitrite about an hour after you do the change.