# Mysterious Deaths and Nitrate Reduction Ideas



## jpostit (Aug 15, 2020)

Hello, 
This is my first time posting to a forum for help (yay!).

Background: I have a 60 gallon tank which is the upgrade from my 46 gallon I had set up for 1 year. I set up my 60 gallon and was able to use the same canister filter and decor I had on my smaller established tank, so the cycle process was pretty easy. I had 8 fish (7 Mbuna African cichlids and a pleco). I set this tank up in April (4 months ago). I hadn't lost any fish in the transfer and one of my fish actually started holding and a few weeks later I found several fry swimming around. I do a 15 gallon water change every week and I clean the canister every third water change. I rinse all the media in aquarium or treated water. I test the water weekly using both API strips and the API master test kit. I have a digital thermometer and a floating one to ensure the temperature remains constant. I feed the fish a small amount 2x day and nothing is left over or even makes it to the bottom. In the canister I have a mechanical filter (black sponge) --> Purigen--> carbon --> bio media. My water tests have been consistently the following: 
PH-7.5-8
Ammonia: 0-.25ppm
Nitrite: 0ppm
Nitrate: 40ppm

Issue: I went on vacation for 1 week and did a water change right before I left. I had a house sitter that fed the fish 1x per day and I rationed all the food out before I left so they wouldn't get over fed. When I returned there was noticeably more brown diatom algae on the rocks and decor and the pleco was nowhere to be found. Upon further inspection, I found the pleco dead in a plant. Its body had not turned white yet and there were no signs of injury so it was definitely very recent. I did a water test and everything looked normal. The next day I did a 15 gallon water change and scrubbed all the decor in aquarium/treated water. My female demansoni looked like she was holding again and was refusing to eat and hiding more (normal behavior when holding). 5-6 days later she was in a strange spot in the aquarium and not quite acting like herself. The next day she was dead and had clearly been picked on by the others. I promptly, did a water change and cleaned the canister filter. I started using Purigen about 6 months ago and had just replaced the packet about 4 weeks ago. However, it was more brown or discolored than normal. When I was cleaning the tank the day after the demansoni's death, I found a fry- so she was holding when she died.

Without any visible signs of injury or disease and my ammonia & nitrite levels being ideal, I am not sure what caused the death of these fish. The diatom bloom and discoloration of the Purigen packet make me think Nitrate poisoning or shock might be to blame. I read that plecos can be sensitive to that but people also say they are very hardy fish, so I don't know! I tested my tap water that I put into the tank and the Nitrate level in the tap is 5ppm. I don't understand why with consistent 25% water changes and Purigen that I can't get the Nitrate below 40ppm. Does anyone have any recommendation for how to lower my nitrate levels or what else I can do to prevent more fish from mysteriously dying? I have thought about using medicated food to treat for invisible parasites but again, I haven't seen any white poop, sunken bellies, or noticeable signs of disease. I even tested the phosphate and silicate levels which were 1mg/L and 4mg/L respectively.

Thanks in advance for your help!


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## Deeda (Oct 12, 2012)

Hi and Welcome to C-F!!

Sorry about the loss of the fish.

What is the expiration date on the API test kit? I will assume you are shaking the snot out of the nitrate reagent bottles prior to dispensing the drops in the test tube so as to get an accurate reading?

I really doubt if you are seeing the deaths as a result of nitrate poisoning or shock. Usually the easiest way to lower the nitrate is to perform a larger water change and since you are doing 15 gallon/25% weekly, try doing a 50% change to get it lower the next time you are scheduled.

Can you post the stock list species you have if you know them?

What decor do you have in the tank as well as what substrate and how deep it is? Do you do any substrate vacuuming at all?


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## DJRansome (Oct 29, 2005)

Also what are the dimensions of the tank?


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## jpostit (Aug 15, 2020)

Thank you for the response! 
When I first got into the hobby, I went with the pokemon "gotta catch em all" mentality, which I know could be part of the problem and if I started over, I would be more careful about who I mix together. I currently have a Pseudotropheus crabro, Melanochromis auratus, Tropheus Duboisi, Labidochromis caeruleus, and a Pseudotropheus sp. Acei, Metriaclima estherae (red). The pleco and the demasoni have passed. The tank dimensions are 48"L, 48"H,and 12"W. The substrate is CaribSea Arag-Alive crushed coral/sand. I do use a gravel vacuum and rake the substrate every time I do a water change to prevent any gas bubbles. A few weeks ago I reset one of the fake plants with sealant made for aquariums. I use Seachem's Prime to treat any tap water before I put it in the tank. The last fish I added was the duboisi in November (9 months ago). The plants and decor are all fake aquarium decorations from my local pet store.


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## DJRansome (Oct 29, 2005)

I would say the males killed the females. With 8 species in a 48x12 tank you want no females and fish that look nothing alike. Also you would avoid super aggressive species like auratus and crabro. Crabro (bumblebee) needs a larger tank in any case.

If you still have females, I would remove them.


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## jpostit (Aug 15, 2020)

Thank you DJ, I got all the fish from the LFS and it is hard for me to tell which are males and female. The auratus definitely runs the tank. I actually haven't seen the bumblebee be very aggressive but the auturas can be vicious. Do you think they killed the pleco too then? Would you recommend replacing the pleco or is it not worth it? I can't tell if there are other females. Most of them have the egg spots on their back fins and none of the others have held eggs, so they might all be males...


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## DJRansome (Oct 29, 2005)

Plecos only have a 75% survival rate so I would chalk it up to that. I would not ever add one fish to an established tank, and I would not put a pleco in this tank in any case.

Would you also consider removing the auratus and crabro? The tropheus will likely not do well.

Egg spots are not a reliable indicator of gender.

Are you committed to the variety or would you consider a mixed gender tank?


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## jpostit (Aug 15, 2020)

DJ, 
I definitely wouldn't add just one more fish. I really liked the demasoni, so I might try to find a male and a couple others. I really like the Crabro and it's one of the OGs from when I first set up my cichlid tank about 2 years ago, so I don't really want to part with him. I would be more inclined to find the auratus and the tropheus a new home, since I figured out after the purchase that the tropheus doesn't really belong in there (but he was so cute with all the spots). I don't even know how to go about finding new homes for them. I am a teacher and with school starting I am not pushing to make any moves or big changes immediately.


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## DJRansome (Oct 29, 2005)

If you are not ready to change the tank or the existing fish I would not add species and not add demasoni.

To manage aggression I would try to get a bunch of yellow lab males. Shoot for 10 cichlids but no variety if you want to keep the crabro temporarily If you make no changes the same thing will happen again.

It is critical that you not add a female...accidentally or not.


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## jpostit (Aug 15, 2020)

Thanks DJ, Sorry it's been a while (school has been off to an interesting start this year...) I have noticed the auturas and the tropheus are the most aggressive and now they have been quite mean to the yellow lab. I think I will get rid of those tomorrow. I do like the variety and I will make sure to not add a female (I think the yellow one might be one). I haven't ever witnessed the Cabro be mean to any other fish but it is the largest in the tank. Thanks for all your help!


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