Nitrate From 5.0 To 10.0 And Fish Sick

[BeckyCats]

This is for a 30 gallon office tank where I work. The person who set up the tank and is responsible for it, went out on medical leave so I have been taking care of it. It was set up about 6 months ago. She did a few partial water changes but never did a gravel vacuum. When she left for medical leave the tank was very dirty and the water was cloudy. I noticed the fish all at the top gasping for air. I researched what to do and learned about water changes and gravel vacuuming. I did a 50% water change/gravel vac and then did another 50% water change/gravel vac maybe 2 days later. I started doing 25% water changes every week and got ammonia down to .25, Nitrates to 5.0 and Nitrites to 0. The pH is always 7.8.
 
Stock: There were a lot more fish because mollies and platys both had babies. A bunch of them died and rotted down in the gravel (I can't even tell you how foul the first gravel vac was). I rehomed all except for the following: 3 white tetras; 1 male orange and black molly; 1 baby black molly (sex undetermined); 1 orange male platy; 2 plecos (not sure what kind but the pet store said they would get 5 inches max).
 
Problem: The male molly has not been doing well. A few months ago the tank was treated for ick but he never fully recovered. He has been swimming sideways and looks thin and pale. In the past few weeks, he was looking a little better and starting to swim straighter. But then, yesterday, I noticed that one of the plecos was dead. I removed it immediately. This morning when I came in to work, I noticed the male molly doing the "shimmy" thing. I have never noticed this before. I researched it and thought maybe he needed to be in a tank with some salt so I just went and bought a small tank for him to see if the salty water will help. BUT when I went to net him out of the big tank I noticed that one of the white skirt tetras was just sitting on the bottom of the tank. When it saw me it roused itself for a second but then just kind of drifted sideways into a plant. I did a water check and the current levels are as follows:
 
pH 7.8; Ammonia .25; Nitrate 10ppm; Nitrite 0
 
What could be happening? The most recent water change I did was 6 days ago. Why did the nitrate level go from 5 to 10? Could this be the cause of the fish doing so poorly?
 
Thank you.

 

[Chad]

Ammonia is likely the problem. A cycled tank should test out at zero. As you pointed out the deaths caused a spike. Keep up on the water changes. 

 

[BeckyCats]

But why now do you think? The fry deaths were months ago and the water has been cleaner for at least 4 weeks now. Could the pleco death have caused the tetra to be sick too?

 

[mark4785]

It could be that the act of vacuuming the gravel has released a lot of ammonia into the water column. The water usually has a milky/cloudy appearance if there is a mix of high light and ammonia in the water as a result of algae spores utilising the ammonia to grow and, later, produce green water.
 
The best thing that you could do is a 100% water change as a higher percentage of total ammonia will be in the form of toxic ammonia (nH3) where the pH and tank water temperature are high.
 
The nitrate level increasing is good sign. It is a sign that that toxic nitrite is being converted by the aquarium's beneficial filter bacterial colonies into nitrate which is relatively safe. My pond fish thrive in nitrate concentrations ranging from 0 to 50 ppm so I would not worry too much about this particular stat.

 

[Chad]

It could be a disease but if you are reading ammonia it leads me to think water quality is the issue. 
 
While .25 isn't what I would consider a highly toxic level of ammonia long term exposure can reduce the immune system of the fish leaving them susceptible to diseases. Vacuuming can also disturb bacteria and release detritus which can cause problems. 

 

[BeckyCats]

I think I wasn't clear in my original post. My apologies. I am upset and perhaps not writing as clearly as I might otherwise. The water is very clear now. It was cloudy before I did the water changes/gravel vacs. It has been clear for about 4 weeks now.
 
I have brought the ammonia level from 2.0 down to .25. I have not gotten any lower than .25 though.
 
A brief history of the tank:
 
~6 months ago tank was set up and did a fishless cycle.
~5 months ago tank was stocked with fish. I assume all levels were good because the person who set up the tank said so.
~4 months ago tank became overrun with molly and platy fry (some died, some lived).
~8 weeks ago fish developed ich and were treated
~6 weeks ago person in charge of tank went on maternity leave
~6 weeks ago I checked water quality and found ammonia to be 2.0 (water was very cloudy). I did a 50% water change while performing a gravel vacuum (I vacuumed about 30% of the gravel). The sludge that came up was black. About 2 days later I did another 50% water change while vacuuming another 30% of the gravel.
~5 weeks ago I did a 30% water change while vacuuming the other 30% of the gravel. Water looked a little better (less cloudy).
~4 weeks ago I did a 30% water change while vacuuming about 30% of the gravel. Water looking clear.
~3 weeks ago I did a 25% water change while vacuuming about 30% of the gravel. Water very clear.
~2 weeks ago (same as 3 weeks). Ammonia level was .25ppm. Nitrate was 5.0. Nitrite was 0. Water very clear.
~1 weeks ago (same as 3 weeks). Ammonia level was .25ppm. Nitrate was 5.0. Nitrite was 0. Water very clear.
Last night found dead pleco.
Today molly and 1 tetra swimming poorly (just looked and saw tetra nose-down in a plant). Ammonia level still .25ppm. Nitrate was 10. Nitrite still 0.
 
There is nothing floating in the water that I can see. The water looks very clear and has for about a month now. I was very careful not to over clean since I read that can be harmful. I will do another water change tonight as well before I go home. How much should I remove? I do not want to harm the remaining fish.
 
Also, do you think I should move the male molly to a saltier tank or would that just kill him since he is used to freshwater?
This probably has nothing to do with anything, but one of the live plants recently (maybe a week ago) developed a blossom or something. Looks kind of like a banana. Definitely a normal plant thing. It wouldn't affect the fish would it?

 

[Byron]

In situations like this, changing more water is almost guaranteed to be positive.  You should check the parameters (GH and pH) of the source water (tap presumably) compared to the tank, but if they are reasonably close, larger water changes will do no harm but will benefit.  The fresh water should be close to the temperature of the tank water.  Use your hand, don't fuss with thermometers for this.
 
Also, clean into the gravel as much as you can at the water changes.  "Over-cleaning" can be a problem, but not here; when you have a situation like this one, the quicker you clean things up the better.
 
I would do at minimum a 50% water change.  I usually do larger changes when there is any problem, up to 70-75%.  Just ensure the parameters are close.  Use a good conditioner, nothing else.
 
I would not move the molly, it will almost certainly die, as will the tetra.  You cannot help either now.  What happened was the ammonia and nitrite.  Some fish will be killed fairly quickly, others appear to live through, but as someone said, these poisons harm the fish internally and they do not recover.  They will succumb to any number of other problems because of the weakened state caused by the ammonia or nitrite.  The molly shimmying is a sure sign of water issues, as is the swimming disorder; mollies are extremely intolerant of ammonia, and tetras are not much better.
 
You have been doing everything you could, so do not feel bad that the fish are dying, and even if all die over the next few days/weeks.  You could not have prevented this, once the ammonia and nitrite increased.  These must always be zero.  Even minimal levels can cause serious issues for fish.
 
It would be worth knowing what caused the ich a while back; ich is caused by stress.  The parasite is or may be present, but healthy fish are able to fight it off.  It is only when fish are weakened by stress that their immune systems are compromised, plus the fish is just weaker in general.  The lack of proper maintenance plus the increase in fish (fry) could have triggered this.
 
Byron.

 

[mark4785]

You should be looking at removing 100% of the water and all the fish to get the ammonia down to 0 ppm. If black pieces are coming out of the gravel I would recommend taking the gravel out and washing it in aquarium water since you don't want to be using chlorine tap water since the chlorine will kill any beneficial bacteria that is present in the gravel of which is responsible for consuming the ammonia and nitrite.

 

[vwdank]

I am just following this and want to ask the question if the carbon cartridge was replaced in the filter after the ick treatment if it was chemical based? I know some treatments say to remove during and it may have no relation on this subject which Is why I am asking. hopefully someone can answer or provide better insight.

 

[BeckyCats]

Thank you all for your thoughtful responses. I am worrying quite a bit over this and hate to think of them suffering. My coworkers think I am crazy for worrying about "just fish" but they are still living creatures and should be kept as humanely as possible. I thought I was doing a good thing by cleaning their tank and now, after a month of cleaner water, they are dying. Did I clean it too fast? Not fast enough?
 
To Mark4785: it's not that black pieces were coming out of the gravel, but rather the sludge itself was black. The first time I put the vacuum down into the gravel and got the suction going, a black plume billowed up into the vacuum. Then, when it went into the bucket, the smell was horrific. The second time I vacuumed, the sludge that came out of the gravel was grey. The next time, a lighter grey, and it kept getting lighter until now it is whitish.
 
To vwdank: when the tank was treated for ick, the carbon was removed as per the instructions on the box. It was replaced when the course of treatment was complete.
 
To Byron: the test kit that is here does not have kh or gh. I have to assume it is roughly the same though since the tank was originally filled with the tap water from here. I'm going to take a water sample to a good aquarium store who will test it. Regarding the water temp, I actually have been using a thermometer to make sure the water is the same temp as the tank. It is no trouble, and I don't want to add to their shock. Poor little critters. I do feel awful. The other person had been using an ammonia block treatment, but I read that those are not good and the way to go is to just clean it up properly, so that's what I've been trying to do. The only thing I add to the water is the standard chlorine/metals conditioner. Regarding the cause of the ick, I think it is exactly what you said: unclean conditions coupled with a population explosion. Actually, they were treated for ick twice. Once was after they were not fed over a 4-day holiday/weekend (this was before I was responsible for them). That incident resulted in a fish death and everyone getting sick. That's when the automatic feeder showed up. Sigh. Poor little critters. Thank you for saying that I am doing everything possible. I really am trying very hard and do care. In fact, I never got an aquarium before because I consider it a big responsibility just like having any other pet. Of course, I now have an aquarium at home because the female molly that was responsible for the population explosion was being threatened with getting flushed. I volunteered to take her so she wouldn't get flushed. Of course, I brought her home and she had more babies but that's a different topic (that's her tail and baby in my profile pic). I do enjoy fish keeping so much more than I thought I would. I thought you had to use chemicals all the time like a swimming pool and it just seemed like too much hassle. Once I looked into it and realized the main thing is hygiene, not chemicals, it is not hard at all. But now these guys at work are doing so poorly.
 
Well, anyway, thank you all, again, for your replies. I am off now to do a 70% water change.

 

[Byron]

My last post dealt with the here and now.  What was done is done and you have to move forward with the results/consequences, and major water changes are the way to do this.  I suggest 70-75% because this is "major," and doing up to 100% would mean netting the fish out to a temporary container, which would be even greater stress.  I go down to a few inches of water when I may need to do this.
 
As you raised the past issues, I will comment on this, for the future.  If the pH lowered below 7, the ammonia would largely become ammonium which is for our purposes harmless to fish.  As soon as you do a water change with basic (above 7 pH) water, and if the pH in the tank rises above 7, the ammonium changes back into toxic ammonia.  So, always test the pH in the tank, and the nitrates, then change water accordingly (little or more, depending).  The ammonia/ammonium aspect is of no matter to the nitrifying bacteria as they use either, so nitrite would result either way.  The black and smell is undoubtedly anaerobic conditions with hydrogen sulphide.  This too is toxic to fish.  So there could have been further problems for the fish from these.  I suppose the best action in such a situation is to set up another tank sufficient in size to house the fish on a temporary basis, using primarily fresh water.  Then clean the existing mess and basically start afresh.
 
Byron.

 

[BeckyCats]

So, I just did the 70% water change and gravel vac as discussed above. Then I tested the water and STILL had ammonia levels of .25 (possibly higher - it's hard to tell from the color difference). This did not seem right to me so I tested the tap water. Straight from the tap. Got the same ammonia reading. Is this possible? Has anyone heard of ammonia coming out of the tap water? Fortunately, I work with people who may know about this so I will ask them in the morning. They've all gone home now though as it is late. I should go home too. I am totally depressed to think that no matter how clean I keep the tank, the tap water is killing them anyway. Oh, and I found the little tetra dead when I went to do the water change. He didn't make it. I did not see any spots on him.
 
The water from the gravel has been a lightish greyish white color for little while now, so it seems like I got that much under control anyway.

 

[ShinySideUp]

Careful with the ammonia tests. I use the API Master Test Kit and it always seems to indicate 0.25 ammonia but since it has done this since I got it and even shows 0.25 on fresh water from the tap I seriously doubt it's indicated reading is correct. Generally if the API kit says 0.25 ppm I assume it is actually zero -- worked so far.

 

[Byron]

ShinySideUp is quite right, this test can be tricky.
 
Ammonia can occur in tap water, as can nitrite and nitrate.  One should always test the tap water for all three.  Keep in mind though the possible test inaccuracies mentioned above.
 
If ammonia is found to be present, this is fairly easy to deal with.  At water changes, use a conditioner that detoxifies ammonia.  The bacteria will easily be able to "catch up" when the level is this low.  Live plants also take this up quickly.  But I wouldn't worry about so low a level, if it is actually present.
 
Byron.

 

[vwdank]

Also Don't get so down on yourself your trying your best at keeping these guys alive. I understand how it can bring you down losing any type of life feeling helpless but you're doing good so don't get discourage no matter what happens.