Back to the basics. Need help with sick fish.. Here is the full story.

Please help.

I have had goldfish most of my life with little to no problems. Boy was I lucky….  7 years ago I moved out to the middle of Wisconsin farm country.  I had a few near tragedies over first few years.  Then out of nowhere in 2016 my largest comet’s veins in his tail turn bright red and he curls up.  I tried many water changes, staying up late at night etc.  I eventually put him out of his misery much to my own misery.  I brought water from the tank to be tested at the pet shop when I first noticed the sickness.  They said it was high nitrates.  I eventually tested my water from the tap and the aquarium specimen side by side.  I was unable to discern one from the other!  My tap water has high nitrates.

After I lost that goldfish I sent a water sample from the faucet into the University of Wisconsin Stevens Point. Here are the results of that test:

This is the most recent data I have for the quality of my tap water.

I reached out via the contact link on this page. Here is a rundown of my operation.  I have lost my way and need some help.  Starting with the basics.

I have 1 sarassa comet (approx. 16”)

1 Common goldfish (approx. 12”) along with a black moor

I also have a brushy nose Plecostomus and a regular one too. 5 fish total.  This is them on any given day

All these guys live in an 210 gallon All Glass brand aquarium with dual over flows. I have approximately 2-3 inches of small rock substrate (similar size to coarse rock salt) a few decorative rocks, an old stump, and a single strand of a broad leafy plant (alive) but unknown type at the time of this writing.  I have used salt in the past (as directed on the API brand container) but got away from its use, and am now back using it.

I have 2 Fluval FX5 canister filters doing my hard work. In each of those canisters has all of the original foam filters.  Each of the 3 baskets in each filter has a decent sized mesh bag of Seachem Matrix bio media stones.  Due to the high nitrates in the water I have used a total of 4 pouches of Seachem Purigen (2 in each filter).  I rely on the agitation across the surface from the pump output for oxygenation.  That is it for filtration.

I have a LED light bar that I set on a timer for evening light for a handful of hours. The tank is in the basement and stay nice and warm in the winter and cool in the summer. I maintain great natural temperature year round.

Cleaning- I have got behind before in this department. The tank has never appeared green, cloudy, or gross at all.  Please do not judge….but when our 3rd child was born I went 1.5 years doing nothing at all.  The water and tank looked clean and all the fish appeared healthy and vibrant.  I did get back on track with the cleaning, but during that time I had absolutely no problems.

I have a Python vacuum to get the junk from beneath the rocks.

When I wash the canisters I only rinse these items. Wringing out the muddy mess into the drain.  The Purigen pouches are soaked in bleach and restored using Seachem Prime (all according to directions from Seachem)  A few years ago I came down with a case of small snails in the filters.  A few have appeared in the tank over the years.  When I see them I dispatch them immediately.

I will give the walls a scrub here and there with a brillo type pad or a magnet scraper.

I have not set up an organized or routine maintenance schedule. I have 3 small children and spare time is a figment of my imagination these days.  But I am hoping to establish something reasonable with your help.

30 days ago I wanted to measure the common comet. I got him 1 year ago at that date and he has grown from approximately 5 inches to 12 inches in 1 year. At that time I noticed that the Sarassa comet had really bright red veins in the tail.  I began daily water changes of 25% – 40% and I completed 4-5 over a week or so.  I added 2 extra pouches of the Purigen and cleaned both of the filters.  I have vacuumed some but still need to do an exhaustive vacuum job.  I added salt which hadn’t been used in a year or so.  And I added Seachem Purigen to cut down the nitrates.  I opened all 3 glass tops and added a submersible pump aiming at a 45 degree angle to add additional agitation to the surface.  I used an air stone for a short time but it lead to more of a mess.

The Sarassa has been laying at the bottom of the tank for a month now. The first week he was aggressively swimming to the top of the tank and gulping air.  A small part of his lower tail fin broke off.  The veins were still red.  It should be noted that BOTH of the other fish appeared fine.  But both changed their normal patterns of swimming around to lay at the bottom with the Sarassa.  They all three lay together still.

As of today the Sarassa veins are light pink and no longer bright red. There is no more gulping of air from the surface. I had curtailed feeding as they used to feed as this video shows  They will eat sinking pellets and I have not seen anyone begging or eating on the surface since this all started.  (so I only use sinking pellets as of now)  I only feed them once a day during this recovery.  And normally they are fed 3-4 times daily.  And boy do they eat when they are healthy!

I hope this story makes sense to anyone who might read it all. I hope to get some help from Venus.  I cannot thank you enough!!



  1. Good to hear that ammonia and nitrites are zero. It’s important that the cycle isn’t broken again. This means being consistent with feeding and maintenance. Avoid rinsing the filters, but if you have to, rinse in old tank water. The filters and pumps is where the beneficial bacteria live

    Are you performing the pitcher method for removing Co2 and keeping tank water temps as low as possible

    The fish will eventually succumb to the high nitrates, so we must bring them down. Could you pick up Prime or Amquel Plus water treatment? These treatment convert nitrates. When you obtain, let me know, and we’ll discuss dosages

    Consider adding bottled water to your freshwater when you perform a water change; at least 30% if not 50%

    Allow algae to build up on the sides and backs of the tank, and if possible, set up a freshwater tub in the sun or under a light so algae can build up. Keep this tub filled with water, and you’ll be amazed at the nitrates the algae consumes. You’ll need to set up a pond pump in the tub

    If you add bottled water, make sure it’s distilled so no mineral value is present. Let’s keep a close watch on KH and GH during this time

    If you wish to raise GH, pick up a bag of Epsom salts with no added ingredients, and we’ll discuss dosage

    Oh…and don’t forget the idea of rain water. The fish may be okay today, but bottom sitting is an indication of nitrate poisoning. A fish’s blood contains the same level of nitrates in its blood stream as the water it lives in. Fish aren’t designed to cope with nitrates. In the wild there are no nitrates in the water they swim in. Plants consume the nitrates as its produced

    Most important…goldfish in water with high nitrates cannot tolerate shallow water. Perform smaller water changes more often; never more than 5%, as this keeps the water table high. You may notice that fish bottom sit after a water change. This is due to the increase in pressure. Deep water relieves the pressure caused by nitrates

    Keep me posted

  2. So sorry on the delay. My water test cam back with a zero reading on nitrates, zero on Ammonia, and the PH level is close to 7.8 (this one is hard to tell on the color chart.
    Nitrates come back blood red. (I am unable to assign a number value to them) I’ll attach a picture of the Nitrate test result

    This weekend all 3 fish surprisingly were alive and swimming around. As if that day her fever broke and she felt good again. There has been some bottom sitting and some swimming. I think the worst is past us. But must now focus on a reasonable maintenance schedule.

    Thank you so much for the help 🙂

  3. This too, consider collecting rain water to use as freshwater in the fish house. Rain water may be low in KH. This is where the term acid rain comes from, but with such a high KH, lowering it a bit won’t hurt a thing

  4. I’m glad to help

    Okay good to know you’re ordering testers. Even though your KH is excellent, these levels must be guarded in an open topped tank, due to water evaporation. Minerals don’t evaporate, so testing to make sure levels don’t climb to dangerous readings is important

    The test result of 7.0 mg for nitrates is confusing. This is a very low reading, and easy to deal with. I wonder if you meant dH, degrees of hardness; measured as 17 plus or minus ppm for each degree. If this is the case, yes, nitrates are a problem in your tap, but knowing is half the battle, and I’m thinking this is the case

    It seems you’re a very savvy goldfish keeper, but dealing with the nitrates in the tap by using the purigen is it? may have caused the spike. The industry doesn’t tell us the real story about their products, and I’m no expert on this product, but I’m pretty sure it’s capable of breaking the cycle, whereas regular water treatments, such as Prime or Amquel Plus do not

    Algae is your best weapon against nitrates. Let it grow on the sides and the back of the tank. Scrape only the front clear. You’ll still have to lower nitrate levels in the tap before adding it to the tank, but the algae will keep levels from climbing due to fish waste

    You need a pond pump in your set up, two actually. The HOBs are okay, but they don’t create the right kind of water movement. Pond pumps pull water from the bottom, pushing it to the surface where Co2 is expelled. Think about it. If you had pond pumps and algae, you wouldn’t have to exchange as much water, therefore, you wouldn’t have to deal with high nitrates like you are now

    I would set up a freshwater tub, and encourage algae to grow in it. The algae will consume the nitrates, if the layer is lush enough. This will take some time of course, but until then, keep the water in the fish house as cool as possible, use Amquel Plus or Prime to convert nitrates in the tap

    If you let me know which water treatment you prefer, and we’ll discuss dosage needed to convert the nitrates. Water treatment can be dangerous if it’s not used properly, but in this case, it’s the lesser of two evils.

    Your pH should be closer to 8.4 or even 8.6 ppm with such a healthy KH reading in your tap, so this tells me oxygen is a problem. Few understand pH, and what it actually means. It’s actually a theory someone came up with years ago, and now the industry uses it as a water parameter. KH test should be used for measuring alkalinity, but pH does pick it up, but low oxygen levels will pull pH down

    With nitrites and nitrates being an issue, the water must be heavily oxygenated for the fish to recover fully

    KH (carbonate mineral) gives water the ability to support oxygen, so if the tank is free of Co2, the fish will be much happier. Until you get a pond pump, perform the pitcher method I described in my previous post, two or three times a day. You’ll be doing what a pond pump does, only manually. Test pH after the fact, and you should see it jump. If not, the KH reading may be off, and O2 levels okay. We can double test KH when you get your kit

    Your KH is high, and total hardness isn’t much higher which tells me magnesium levels are low. Magnesium is a part of GH, and all important. The other part of GH is calcium, which is common in most regions, whereas magnesium isn’t. Increasing these levels is easy, and could help your fish quite a bit in easing their symptoms, and relieving pain. We’ll wait until you can test to be sure, and then discuss buffering these levels if need be

    Every fish house is a work in progress

  5. Your fish are fantastic, and I love hearing about them living in a large tank; happy fish. No one here will judge you. We’ve all made the same mistakes, and we’re here because of it, for one reason or another. The salt treatment you gave the fish was beneficial, as salt contains chloride which improves gill function, which helps fish get oxygen, but tread lightly. Salt can injure the fish, and most salt boxes from the pet shop instruct with too much salt. A little goes a long ways

    The red streaks are enlarged blood vessels caused by nitrite poisoning. There was a spike in the cycle

    Do you test toxin levels regularly? Do you typically have a reading for nitrates? If so, what is the average reading? Every good fish keeper needs a master test kit. Toxins need to be tested at least once a month in a well established tank. I don’t test for ammonia or nitrites unless I’ve done something different or something has changed

    When we feed our fish, we’re also feeding the beneficial bacteria that create the cycle. To keep these delicate creatures healthy, we must feed frequently and consistently. Our fish like being fed frequently as well. They have no stomachs, and can only digest small amounts at one time. Feed less more often

    It’s important to establish a maintenance routine, and stick to it. You say you left your tank unattended for a long period of time? Oh…it was attended alright, by Mother Nature. As soon as she saw her chance, she took it, and she did a great job didn’t she?

    What is the nitrogen cycle? Without it, there would be no living creatures in our natural bodies of water, which is the basics….of life. It all works so beautifully. The fish make waste, and from waste ammonia is created; a dangerous toxin. Oddly enough, there is a type of beneficial bacteria that feeds on this toxin. It appears magically when conditions are right, and ammonia is present. This friendly bug changes the ammonia into nitrites, another dangerous toxin

    Toxins..ammonia, nitrite and nitrates are friendly bug pooh

    When nitrites are present, another type of friendly bug appears to feed on the toxin, changing it into nitrates. Your fish may or may not have suffered nitrate poisoning. The blood streaks appear long after the toxin has come and gone; damage done. Nitrites and nitrates both rob the blood of oxygen, thickening it, only the symptoms are different

    It’s true that fish poisoned by nitrates curl, but this is the last symptom to be exhibited before death. The first is laying on the bottom, often pressing it’s body into the gravel to get deeper and deeper. The pressure caused by the weight of water relieves the pressure of nitrate poisoning. Fish suffering from nitrite poisoning only, don’t sit on the bottom or curl

    Another thing that causes the same symptoms of nitrate poisoning is supersaturated gases; SSG. These are gases in tap water caused by water being forced through pipes. If you have SSG in your tank, you’ll see the bubbles clinging to the sides of the tank, and if there are enough, even the fish. They can be absorbed into the bloodstream, and cause the same condition as nitrates. They can also get beneath the tissue, cluster in pockets beneath the skin, looking like tumors. It’s strange

    You would know if SSG was an issue, because you would have noticed the tiny bubbles on the walls of the tank

    I doubt you’re testing regularly because you’ve taken samples to be tested, and have said nitrates were high in your tap, but you’ve given no readings

    Get a master test kit. Even an expert can’t keep water well without knowing. The trick is…understanding the readings, and knowing what they mean. It all sounds complicated at first, but once you get it, it’s fascinating…water

    We need to know just where your cycle is at. If there’s ammonia, nitrites or nitrates, and just how much. The goal is nitrates only. You’ll hear people say that nitrates are the end result of the nitrogen cycle, but it’s not true, nitrates is the final toxin to be converted, but not the end result. This is where algae comes in. The stuff you scrape off the walls of your tank, in an effort to make it look good. Algae feeds on nitrates, keeping levels at bay. If you have healthy water with a healthy level of nitrates, and a little light, algae forms. Algae is a great food source for fish

    A lot of people make the mistake of feeding less and less because they believe waste is causing issues, but waste is where it all starts, and not just any waste. In order for friendly bugs to feed on and convert toxins, the ammonia the waste is created from must contain enzymes; the very enzymes that are in the waste fish produce. This is why it’s next to impossible to build a healthy cycle from any other type of waste

    That’s our lesson in the cycle for today

    Open your tank so the water is exposed to fresh air, as this is how water is oxygenated. The movement of the surface pulls oxygen from the air. The room the fish house is in should be filled with fresh air. Goldfish are cold fish. They like temps between 60 to 70, but can tolerate a much lower being cold blooded. Cold water places them into a dormant state. Anytime you think your fish have an issue, lower the water temp. They’ll need less oxygen, and will sustain less damage, buying time to fix what’s wrong

    Your fish needs heavily oxygenated water in order to recover fully. I need to know pH, KH and GH. These are tests that typically come with a master test kit. It’s better to buy a kit and learn how to test than to rely on the pet shops. They don’t know. They don’t care. Their idea of a reading is safe or unsafe, but we need real readings in order to examine the water closely

    Until you get a test kit, or can provide test results, lower the water temps to 64f. Use ice or freeze tank water in the fridge or open a window. lol I feel a cold chill coming on here in MO, and I would bet it’s colder in your region

    Do you remember just what the nitrate readings were for your tap?

    After you remove the glass from the tank, using a pitcher, push it deep in the water filling it. Bring it up and pour the water back in. Repeat this process 10 times, three times a day. This will remove Co2, gas created from the waste your fish produce.
    This gas fills a body of water, keeping oxygen from entering. The added movement will also pull in oxygen from the air

    Soon well discuss your set up, filter and gravel and so forth

    Thanks for visiting the site, and posting as well

    1. Thank you so much for the well written and thorough response. I have been lucky for so many years just bumbling through the process and still raising some mega comets. But now it is time to go back to school and get this right. I am ordering a test kit to get the kh and gh levels as my API master kit lacks those tests. I will aim to perform a battery of tests this weekend (hoping the kids will oblige) will post pics and results as I can. Again, I cannot thank you enough for the lesson. – Matt

      Do you test toxin levels regularly? – NO. sadly, but when I do the Nitrates reading comes back blood red. the University tap water test I sent in read Nitrates 7.0 mg/ l N hardness-total 173 mg/l CaCo3 Alkalinity 138 mg/l CaCo3 ph 8.08 std units and chloride 9.3 mg/l

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