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New tank syndrome in established tank, or something else?
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Joined: 26 Dec 2010

PostPosted: 2010.12.26(Sun)20:54    Post subject: New tank syndrome in established tank, or something else? Reply with quote

Hello all! It has been a number of years since I had to post for help, but I've got myself into a pickle and I need another experienced head to examine what is going on in one of my tanks. Tank in question is a 125 gallon planted freshwater tank. Tank has two Whisper 60 rear mounted filters and 1 Fluval 405 canister. They have been in continuous operation since Spring of 2006. I had let the tank population dwindle because I was considering changing it from a Rainbowfish piece into an African Cichlid tank. In the end, I felt the pH stability was too challenging to change, so I decided to stick with what I've done best over the years, primarily Rainbows. A month ago, here is where the population stood:

1 M. Boesmani Rainbow @ 5.5" (very mature)
2 M. Morgurnda @ 4.0" (mature breeding pair)
2 Botia Almorhae @ 3.0"
1 A. Spilurus @ 5.0" (last of a home bred school from years ago)
1 Brochis Splendins

Typically I do 25% water changes weekly. Source water is tap. Normal water parameters are 78 degrees, pH of 6.2. In preparation for adding new fish, I did a slightly larger water change just to make sure the top gravel was completely disturbed/vacuumed. I probably replaced about 45 gallons of water and let it sit overnight. Everything was fine in the morning, the fish were happy and vibrant. I ran all the tests you'd expect. pH was 6.2, ammonia was 0, nitrite was 0, and the nitrates came in very low, between 3 and 5 ppm. This seemed normal, the tank was barely stocked after all. So, off to the LFS I went. Very Happy

I came back with 6 more Brochis Splendins, 6 very small Botia macracantha, and a pair of quarter sized parrot cichlids. Prior to introducing the new fish, I tested their water from the store for pH and it came in at 6.8. Given that their reading was slightly higher than my tank, I slowly acclimated them and released them. The fish seemed perfectly fine in about an hour. As a general rule, I don't feed new fish. So I skipped the nightly feeding. In the morning I gave them a light feeding of Aquarian flake food. At night I gave them the usual feeding of frozen bloodworms. Still, all was well.

36 hours after the fish were added, I noticed the water turning hazy. Shocked I thought, oh boy, here it comes. I've heard of this happening, never had it happen to me. New tank syndrome in an established tank. I tested the water for ammonia. Nothing. I ceased feeding completely at this point. I continued testing the tank about every 8-9 hours for ammonia, nitrite, and pH. The pH never changed from 6.2 and my ammonia and nitrite readings kept coming back at 0. Yet, before I knew it, all of the new Brochis and Botia species were displaying signs of ammonia poisoning. Mad

Clamped fins, whitish streaks on the sides, red inflamed gills, listlessness. I was so convinced that ammonia was present I went and bought new testing kits and blamed my prior readings on old stock. The new kits continued to bring me readings of 0. Not knowing what else to do, I tried to manage things by doing 25% water changes twice a day, once in the morning, and once at night. At one point, about 3 or 4 days into this, I did get a slight reading of about 0.25 ppm on ammonia. By this point, fish were dying off. I lost half the loaches and half the Brochis catfish in about 3 days. Within 96 hours of the water getting cloudy, all of the new fish were dead, but more disturbing, some of the old timers were beginning to get ill. By the end of a week, I lost my remaining Boesmani rainbow who was very old, and also my last Spilurus cichlid. About 10 days after the cloudy water first appeared, I was down to the original Brochis Splendins and only 1 M. Morgurnda.

So I let things settle down for about 2 weeks and just kept an eye on the tank. The water returned to crystal clear. Even after getting the reading of 0.25 ppm ammonia, I never got a nitrite reading. My highest reading on nitrates came in at 5 ppm, which if anything, led me to believe the nitrification process was working just fine. So, about 10 days ago, I went to a different fish store and added six M. Praecox rainbows. These fish have been doing just fine. They are active, eating healthy, and acting crazy, like rainbows. Wink

2 days ago, I went back to my other LFS for 6 more Brochis Splendens and another pair of parrot cichlids. I added these fish Christmas Eve. They were doing fine Christmas day. Today, I just about fell over when I found one of the new Brochis catfish laying belly up on the bottom of the tank. The new parrot cichlids, who are about 3.5", are clamping their fins and refusing to come out of their rocky holes. Their gills appear agitated, their eyes have white spots in the middle. All of the remaining new Brochis Splendens have white edges to their fins and white stuff on their eyes as well. Evil or Very Mad

The Praecox rainbows? Nothing abnormal. Water currently tests at 0 ammonia, 0 nitrite, 5ppm nitrate, pH 6.2

So now, I am really puzzled. Even if I never got the readings I expected, I am convinced the first disaster I had roughly a month ago was due to adding too much stock at once, overloading the biological system, causing the cloudy water and an ammonia spike, which killed all the new fish and most of my existing stock.

Now? The original Brochis catfish is doing fine, the original Morgunda gudgeon is doing fine, the week old Praecox rainbows are doing fine, but the new catfish and parrot cichlids are going through a remarkably similar event. Could it be that the pH change from LFS water from 6.8 to 6.2 is causing this? I've made this kind of swing before with no issue. If their water was originally say, 7.8, I'd be muchmore apt to blame this first. I'm hesitant to do anything that might bring the pH in my tank up, because the other 8 fish are fine. I would like to save the new fish, but I am not sure how. I do not have a hospital tank at my disposal, I am afraid.

I am just at a loss as to what all this means and what to do next. Needless to say, I think I'll stick with the store where the Praecox rainbowfish were bought!
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Joined: 13 Feb 2006
Location: Denmark

PostPosted: 2010.12.27(Mon)14:54    Post subject: Reply with quote

In preparation for adding new fish, I did a slightly larger water change just to make sure the top gravel was completely disturbed/vacuumed

I would say you vacuumed the gravel too good and desturbed the established aerobic/unaerobic bacteria + the mulm was acting like a cation exchanger keeping the ammonia and other nasty gases in the ground.

I did this in a 600 litres fish system at work and it took only a few days to experience massive fish deaths.

If you do such thing again in the past add Zeolite and Active Carbon to the filters.

I can't find any other issue with this set-up unless the newly purchased fish came streight to your lfs from lets say south east asian distributor without satying in the quarantine for 14 days. This sadly happens often these days where lfs buy fish directly from SEA distributors and skip the quarantine time.

friendly, Dusko
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Joined: 22 Jan 2011
Location: NSW Australia

PostPosted: 2011.01.23(Sun)20:43    Post subject: new tank syndrome Reply with quote

Just to express empathy and shame. I am less experienced and have a far more modest setup. A couple of days ago planted new weed in my 20 gall high and added few extra neons. Only small no. neons, 1 BN and sword additional in tank and had just found home for sword. Planting and making neon school size respectable was in preparation for a dwarf gourami in a few weeks when things settled. Well the BN is a bit lethargic today and sitting on the filter intake. I had another BN in another tank that did that. When he didn't move for a couple of days I gave him a nudge (they usually scuttle off indignantly). Well this first one I had just floated off the filter and settled gently on his back on the bottom, little sucker mouth smiling peacefully up at the surface. That was after the introduction of new weed and maybe a new fish. I am also now worried about this BN and the fact that I won't be able to return the sword if he gets sick.

Well I now understand the enormity of stirring up the gravel. I spent ages trying to rearrange the "furniture" - digging around trying to get the weed in the right place, making sure driftwood looked balanced, etc etc etc. I went in there again and again and now realise what I might have done. I have not had to treat my water except for dechlor etc for tap water changes, and get it tested in the shop prior to new introductions. I'm off to the shop now and will obviously have to learn how to do the ammonia nitrate and nitrite balances myself. No new fish until I learn ....

Your post listed a few things on what not to do. I knew I shouldn't root around in the gravel in a tank full of fish, but just had to get those plants right! I hope that everything works out for you. I'm off to the shop to get the water tested.
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