Tetras Dying Off One By One

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Jul 19, 2016
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Hello Everyone,
I'm new to this forum and relatively new to fish keeping (a tank when I was a kid that got neglected doesn't count).
I recently dove head first into this hobby and I love everything about it.  I have decided to keep angel fish as my main focus for my new tank - a 37 Gallon tall (30x12x22) - and decided that I would also buy some schooling fish to go around them.  When I was at my LFS they had a batch of Black Phantom Tetras that were beautiful and the employee was telling me that he had never seen a batch come through looking that good.  I bought 6 along with my two Angels.
I started to watch them carefully, as I typically do, and noticed that one of the two males wasn't schooling with the others.  He seemed almost in a trance with his mouth opening and closing quickly and then he would start to tilt one way and then twitch upright again.  This repeated itself every 2 or 3 seconds.  He died a little over 24 hours in the tank.  I was watching when he finally kicked it and got him out immediately, but I noticed one of the females separate from the group doing the same behavior as the male.  She died the next day.  I am now looking at one more female in the corner repeating the process.  I'm a little worried that whatever is killing them is going to take out the whole school - or heaven forbid the rest of the tank - but what really concerns me is my two angels I bought.  My first instinct is that this could be NTD which can also transfer to angelfish.
Has anyone else seen this behavior?
Hopefully the next couple of paragraphs will answer the questions you will want to know.
The tank has a fully cycled filter on it.  it is an AC30 moving 150GPH.  I recently changed from my starter 20 gallon to this 37 and the filter had been running there for a few months.  When I bought the new fish I also upgraded to an AC70 filter, but am running both currently so that I still have one cycled while the other one builds up the bacteria.  Before adding the 6 tetras (2M-4F) and 2 angles I had 5 platys, 2 small honey gouramis, and 2 fancy guppies.  These fish were bought primarily to cycle the filter and prepare for whatever my main fish was going to be.
Due to the relative in-expense of the starter fish, and the fact of my system currently running with both of my filters I couldn't quarantine.  I will be using my 20 as a QT with the AC30 as soon as I can.
My water parameters are consistent at 78 deg F, ammonia is typically 0PPM (the last couple of days after adding the new fish it has gone up to 0.25PPM), Nitrites are 0PPM (i'm assuming it will go up as the bacteria builds shortly), and the Nitrates are always between 0 and 5PPM.  I do a waterchange atleast once a week of about 30% and feed once a day what they can eat in about a minute.  My PH is a little high and I'm trying to figure out what is causing it.  My tap water is 7.6 - 7.8 but my tank always tests at 8.2.  I use an API liquid test kit, and API tap water conditioner.
Please let me know if you have any ideas of what I should do, or what it could be.  I really hope that I am not somehow causing these fish to suffer and die.
I would suggest you sort out the pH issue.  While minimal differences in pH can be tolerated, a major shock could cause what you are seeing here.  You also need to know the GH and KH of your source water as these are part of the pH relationship.  The GH/KH you can ascertain from the municipal water supply (if you are on city water and not a private well); check their website for water data.
When testing tap water pH, you must ensure the CO2 is out-gassed as this can cause inaccurate (and lower) readings.  Let a glass of tap water sit 24 hours, or shake a jar of tap water very briskly for several minutes which will be sufficient for our purposes.
I won't get bogged down in the chemistry until we have these numbers.  But it would also help to know how you acclimatize new fish to the tank.  And another point is that the fish might have something--can you check with the store and see if any of their Phantoms have showed these symptoms or died?
I would not jump to the conclusion that this is NTD.  Behaviours such as you described would tend to indicate something in the tank water, and having eliminated ammonia, nitrite and nitrate with your tests, it leaves us with the GH/KH/pH shock or something with the Phantoms themselves.  My inclination is to suspect you may have fairly hard water, but I need the afore-mentioned numbers to pin this down.  How are the angelfish reacting?  [You may be in for issues with the angelfish but that is something we can get to later.]
Hi Byron,
Thanks for the response.  Update: the fish that was acting funny yesterday is still alive.  Maybe not back to normal, but she is still among the living.
Now, the numbers.
KH/GH are both approximately 120 (5-in-1 API Test strip...I know not the most accurate, but it's what I have handy).  It may also be worth noting that the strip put my PH at about 7.8.
I acclimate the fish by floating the bags in the tank.  Typically I do this for 15 mins.  This time in particular I got a little busy with some other things so I'd say it was more like 20-25 minutes.  After the float I pour the bags through a net into a bucket and transfer the fish from the net into the tank.  I don't pour the LFS water into my tank.
I have called the LFS twice (after each death) and they said that the fish were still for sale and that they didn't believe there was a breakout of anything in the tank.  I kind of got the impression some have died, but I'm sure there is a "normal" amount to expect in these situations.
I do have a water softener in my house, but I haven't used it in a year or so.  I tend to like the taste of the harder water better, and my original plan was to keep african cichlids so it made sense to not use it.  I had to abandon that plan as the area of the living room my lovely wife has graciously allowed me to put a tank doesn't have the footprint to properly support africans.
The angels are acting totally normal.  One is almost always at the bottom of the tank cleaning the sand or making it's way up one of the plants picking algae off.  The other swims around as though it is the most proud fish I've ever seen.  The marbled one had a white spec on it's tail fin that worried me for a little, until i realized it must have got nipped.  I added some salt (1tbsp per 5g) and the next morning it was gone and the fin looked great again.  Perhaps it was just sand.
I'm not clear on the tests issue.  Concerning the pH, we need to know the pH of the tap water alone as well as the tank water.  The tank at 8.2 when the tap is supposedly 7.6 needs to be sorted out.  Did you out-gas the tap water before testing?
The GH/KH at 120 I assume is 120 ppm (parts per million, which is the same as mg/l) which is around 7 degrees (some of us prefer the lower d unit, so I tend to use both).  This is soft water [no where near adequate for rifgt lake cichlids, or livebearers either, but perfect for soft water fish like tetras].  You are certain this is not going through any water softener?  Softeners generally are bad for fish as they usually add sodium salt.  But we must pin down all these numbers so we know where we are starting from.
And it really would help to confirm the GH/KH and pH with your municipal water authority; have you looked for their website?  Especially since you have harder water fish (the livebearers like the platy, guppies are less finicky) and these will not be in the best health.
Turning to the acclimatization, you should add tank water to the bag (or bucket) containing the fish in the store water.  The idea is to mix the tank water in slowly so any differences in GH, KH, pH, and TDS (total dissolved solids) will be more gradual.  I know this is not going to deal with major differences as it is still too rapid, but hopefully the situation in your tank water will be better than the store water and not too much of a difference.  Characins (the tetras) are rather delicate fish that have low tolerance for fluctuating water conditions, and shock from any of these could cause what you saw.
Let's hope the angelfish are females, which may prevent problems.  Males are highly territorial, and two, three or even four angelfish with more than one male is a recipe for disaster.
Hi Byron,
I just lost a honey gourami tonight that I've had for 3 months.  This has really made me think harder about what has happened in the life of my tank.
For the past 6 weeks give-or-take that gourami has turned from orange to almost white.  The other one, bought from the same batch, seems fine.  I think in my head I was attributing it to a new LED light I bought, and changing from black gravel to filtration sand and the general difference in the look of the tank.  My yellow platy's appeared way more vibrant under the new conditions, it didn't seem unreasonable an orange fish may fade.
I think you are correct with the pH being the main culprit at the moment.
I have tried to confirm the kh/gh with the municipality.  The website doesn't have anything listed.  I live in a small community in Southern Ontario and frankly I'm surprised there is a website at all.  I will try to call them and see if they have any results they could send me.
I have been using an app on my phone to track my water tests and I had forgotten that the very first few tests showed a rise in pH from 7.5 the first night (April 2) to 8 the next night, and a couple nights later 8.2 which is where it has been since April 6.  I am guessing this implies it is my decorations.
I tested 24hr old tap water for pH and it tested 7.6.  I have pulled out my decorations (two fake plants and a fake log) and put them in a 5g bucket with some fresh -untreated- tap water.  I'm going to test it tomorrow and see what the pH of the bucket water is.  Assuming it is around the same as the tap water will help me know my decorations are ok.  I will then treat the water and let it sit again to confirm that the conditioner I'm using isn't somehow altering the pH.  
I also noticed that my heater seems to have a buildup of white mineral on it.  My guess is calcium.  Our water here is usually full of calcium and you end up with anything that holds water being covered in it eventually.
Is there something else I should be doing?
My water parameters are consistent at 78 deg F, ammonia is typically 0PPM (the last couple of days after adding the new fish it has gone up to 0.25PPM), Nitrites are 0PPM (i'm assuming it will go up as the bacteria builds shortly), and the Nitrates are always between 0 and 5PPM.
In my experience nitrogen levels like that are typically associated with higher levels of phosphate and potassium.  Those can be toxic at high levels.  Although they may not show up in the standard GH and KH  or PH tests.  There are tests for phosphate and potassium but they are frequently hard to find.You may want to increase the amount of water cycled out per week to help eliminate the possibility of excess potassium or phosphates.  
I would not finger ph as the cause of the problem.  However it could be a symptom of the problem  I have seen PH levels go up to about  8 witout seeing any effect on my fish.  
Responding to your issues in post #5...
The 6+ week issue with the gourami would not seem to be related to something possibly introduced by the new tetras.  If I read post #1 correctly, the tank was initially cycled with fish, including the gourami.  That may have triggered the gourami demise.  I would not expect much trouble from so few fish in a 37g, but it is still a possible issue.  And fish that live through cycling do not remain healthy, depending upon the extent to which they were affected.  Subjecting a fish to stress usually means long-term damage has occurred internally and this can show up weeks and even months later as something completely different.  Another possibility is something wrong with the gourami itself.
To the water parameters, we still need to pin these down; if you can post the link to the website you found, I may find something useful.  White deposits suggests calcium, and thus hard-ish water, opposite of the test numbers posted earlier so something seems to be out here.  The pH rising I had expected to be due to the CO2 issue, but if that is definitely ruled out (though I would vigorously shake some tap water and test again) it may be due to calcareous substances in the aquarium, which can be the gravel or sand or decor, though more likely the sand.  Fake plants will not be calcareous, though the log might, but the sand is more likely still.  "Filtration sand" I take to mean pool filter sand, and this could be calcareous.
Black Phantoms are not robust fish, and any fluctuations in water chemistry can have impacts on them.  Their demise may be related to whatever killed the gourami, or not.  But we must have all the data to sift through, as there are so many factors involved in a fish tank and fish can be severely impacted by any of them.
This is a bit off topic, and I appologise for that, but an earlier comment worried me. It concerned a water softner. There are a few different types available, but a common type uses an ion exchange resin, one that works for a while, then has to be "recharged" by running a concentrated salt solution through it. It might not be obvious, the softner may require periodic sessions with a special "cartridge" or similar process. These work under normal use by extracting divalent Calcium and Magnesium ions and replacing them with monovalent Sodium ions, ie. for every Calcium or Magnesium ion they extract, they release two Sodium ions. These systems should not be used in aquariums, and certainly should not be drunk. Google "excessive salt" for pages listing the numerous problems this can cause to animal life, human included.

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