10-23-2012, 02:15 PM
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Fish deaths and stress, can't determine cause (a bit long)
Hi all, I'm having some issues with my 29 gallon tank. It's been fully cycled for two months now and I regularly check levels with my master kit. The tank is the planted tank in my profile. Everything was going well, I had stocked two schools, 8 Bloodfin Tetra, and 8 Zebra Danios. They were so active I was calling it my "fish in a blender" tank and everyone seemed pretty happy. The Danios were spawning quite a bit. Over the past week I've lost all but 2 Danios (2 at a time, overnight) and the Bloodfins spend a lot of their time huddled together behind a piece of driftwood planted with Java Fern. They are all eating well.
My normal routine was a 50 % water change every 6 days with gravel vacuuming of the areas that wouldn't disturb the plant roots. I use Prime for my conditioner. My ammonia and nitrite were consistently 0 but my nitrates were inching up towards 40-ish (seems like there are always bits of plants decaying no matter how I try to "garden"). pH is 7.4, no change, and temp is 77.5. I decided to get a water changer to make the changes easier last week and I did two 50% changes 3 days apart to get the nitrates down to a more manageable level. That's when the deaths and stress behavior started. I was very careful to add enough Prime before I refilled the tank with the changer, the water temp was within 2 degrees of the original water. I added enough Prime for a 50 gallon to be safe because it says you can safely double dose and I was a bit paranoid about adding tap water straight to the tank. I would have thought the water changer would be less stressful because I'm not having to pour water back into the tank and disturb anything.
The only thing I can think of that may have made a difference is that I lifted the two pieces of driftwood and vacuumed under them on the last change. Is it possible that I disturbed an anaerobic pocket? From my reading I thought it would take much longer for those to occur, and I do have snails in the tank (hitchhikers and 4 assassins to deal with them, although I'm not sure if all the assassins are still alive, they hide so much) so they should be helping with the aeration, right?
I'm a bit frustrated at the moment because everything SHOULD be fine but something obviously isn't. Any suggestions would be helpful.
10-23-2012, 02:32 PM
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Your nitrate levels are pretty high. Are you over feeding? What kind of food do you use?
I know that snail deaths result in a explosion of ammonia. Is it possible that you could have missed that?
Have you added any salts or products besides Prime?
What kind of filter are you using? Did you ever wash the filter? Was the filter ever left off for significant amount of time?
What kind of substrate are you using? How deep is it?
Have you recently added any fish? Do the fish look bloated, swim strangely, or have any unusual marking or spots on their bodies? Does anything hang out of their butt? (Weird question I know)
Last edited by AK Fresh Water; 10-23-2012 at 02:37 PM..
10-23-2012, 08:10 PM
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I don't think I see anything here that might explain this, so we need to examine a bit closer.
The rise in nitrates is interesting, they should remain stable if the tank is now looking much as it does in the photo with those plants. [Nice aquascape, by the way.
If using the API liquid nitrate test, are you shaking Regent #2 for a good 2 minutes before adding the drops? If not, do this and see what reading you get. And nitrates in the tap water with this kit are 5ppm, just to confirm?
Adding Prime when you begin to fill with tap water is fine; it is instantaneous. There is no chance of chlorine poisoning with this.
Are the fish showing anything odd, in colour, appearance--spots, blotches, patches, frayed fins, closed fins... anything? Are the bloodfins harassing the danio at all? And these fish have been in the tank how long?
10-24-2012, 02:03 PM
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Originally Posted by craftyjag
Hi Byron, the fish have been in there for 6-8 weeks (I added them about 4 at a time over a couple of weeks) and were very active and eating like little piranhas. Both schools chased each other around within their own schools but not really Danio to Bloodfin or vice versa. No real aggression or nipping, just really active. I seemed to have 5 or 6 female Danios and they constantly appear heavy with eggs, at least to my inexperienced eye. There didn't appear to be anything wrong with them and I usually sit and watch them eat to see how everyone is doing.
I'm very careful to shake and tap and do the Cha Cha with the Nitrate bottle each time and they've never gone over 40-ish but with the two water changes last week I was trying to bring that down further. I've tested the tap water a couple of times and it's always 5 ppm and the water utility report also verifies this. My plant growth seemed to have stalled a bit so I pruned back the Water Sprite during the water changes to add a little more light, so the tank was brighter than it had been. I can see that possibly contributing to the stress but not the deaths. I use Seachem Flourish and root tabs for the plants. I did add more of the tabs with the last water change but they were overdue (the ones I had were API and say they last a month).
The Tetras did come out and get more active tonight but are staying near the bottom of the tank. The two remaining Danios are behaving normally and are active and near the top of the tank as usual. I'd like to replace their school but it's a little scary at the moment!
I failed to mention that I'm having a bit of the new tank brown algae but after reading up on it I'm not too worried about it just yet. I noticed tonight that there's a light sheen of green algae on the tank walls (you can see it if you look at the tank from the end) but I'm assuming that's because I added more light and had the higher nitrates and slower plant growth for a while. I'll scrape that off with the next water change.
Certainly do not add fish yet. A fish may die and who knows why; but when several die close together, one needs to try and determine the cause. If this demise stops and the fish continue to appear fine and normal, and this lasts for say 3 weeks, it should be safe to consider more fish then. Can you quarantine new fish in a small tank?
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