Unexplained Fish Death

[nerbaneth]

Hi,
Unfortunately this morning I lost half of my fish in my 90 gal.
my main concern is how to treat the tank so I can put the other half back in.
Last night my tank was crystal clear, and this morning it was cloudy and white. I did all of my tests and the only thing that appeared slightly high was nitrites (1-2ppm)

My tank did not become too warm overnight as to fry my fish, My filter is still working fine, The tank is well established and cycled, I did a 50% water change a week ago

I already consulted 3 people who I believe are more knowledgeable about fish than I in my area - none of them had any clue what my problem is.

My thoughts are that this could be caused by 3 things :

Algae that removed all the Dissolved Oxygen and then died (but this happening overnight in a 90 gal in unlikely)

Some kind of bacteria in the tank - if this was the case do I need to take everything out and sterilize it?

A chemical somehow made it's way into the tank (I haven't added anything to the tank since I fertilized 2 days ago (today was supposed to be fert. day)

R.I.P. - 2 bala's (Dos and bala) 1 electric yellow cichlid(bannana fish) 1 german blue, and 2 pictus catfish

Thanks,
Nerb

 

[VaughnH]

Is overfeeding a problem for you? That could gradually build up decaying food in the substrate, causing a bacterial bloom. Do you use CO2? DIY CO2 can sometimes get too much yeast in the tank. Pressurized CO2 can sometimes get to too high a concentration. One dead fish, not noticed by you can cause a massive bacteria bloom if the fish is big enough.

 

[nerbaneth]

thanks for your responce Vaughn!
I feed what they can eat in 3 minutes (usually there isn't any left) I have a diy co2, but it is rare to get any of that liquid into the tank (the tubing is always dry and still was this morning). I couldn't find one fish last night, but it was a tiny one.

I did a 50% water change, and the water is about 50% as clear as it was before (still pretty cloudy) should I try a water clarifier? I was just noticing that even my plants are starting to look upset now. I think if everything is still bad tommorow, it might be time to take EVERYTHING out and wash/disinfect. - this means I will have to cycle again if I cleaned out my canister too

I actually have pictures from yesterday compared to today if anyone would like to see them and I could take a current picture (maybe even some closeups of the plants)

strange to see a perfectly fine tank flip around in one night.

 

[Panda]

any plumbing work in your house lately? any pH adjuster?

I only mention that because those where 2 troubles I had about a year ago and copper did kill many IFGA guppies ! and the ph because I had a problem once when I used to be very concern at keeping them an 7.5 pH and the water turn cloudy.

 

[nerbaneth]

no recent plumbing, I use seachem acid buffer about once a week (I have some 'found' rocks that would love my water to have a ph of 8.0)

 

[VaughnH]

There is one major problem you are making. Using acid buffer is virtually always a major mistake in a planted tank. You might possibly be right to use it in some circumstances in a fish only tank, when your water is very hard, but I can't think of a situation where it would be beneficial in a planted tank.

The "found" rocks you have are dissolving in the water, increasing the KH and GH, and making the pH of the water go up. As you continue to add acid buffer in an attempt to keep the pH lower you are just increasing the total dissolved solids content of the water, filling the water with unneeded ions. Eventually that will kill the fish, and may have done so for you.

 

[nerbaneth]

I didn't know acid buffer was bad. when I started using it, my plants seemed to notice the difference. (don't my plants and most freshwater fish become unhealthy in a pH of 8.0?)

The acid buffer I use says its designed for planted tanks and converts KH to CO2(is that the releasing ion part?) - strange to think it will kill fish. I only usually add it on water change days. So should I stop using it all together and live with really high pH?) (I can't afford a RO or to buy RO water from the store every time i need to refill)

anyway - my water is still very cloudy. Does anyone think that I could use alum to flock the particles since there is no fish in there? aluminum sulfate is a common additive to drinking water treatment, and also used to remove algae or snails (I forgot which one) on plants - people soak their plants for days with this stuff (so it must be safe for plants too) or should I use a clarification product from pet-co/smart that says safe for plants?

or should I continue daily 50% water changes until it is gone?

Thanks so much!
-Nerb

 

[Panda]

following Vaughn's line... I have hard water in my house . If I only add tap water to my tanks the ph will climb up to 8 in a few days. Everytime I do a water change I add a few gallons of RO water.

 

[nerbaneth]

would 5 gal be enough ro water for a 50% water change on a 90 gal tank?

so.. 90 gal minus dirt rocks and plants is prob. 70 actual gal.. 35 gal is a 50% WC.. that makes 5 gals - 14% of the water added. maybe 10 gal/30% of RO added to the water changed would be more appropriate.. it would only cost... $2.50 a water change for 10 gal of RO water from the machine. would I need to add anything like gh booster or baking soda and trace if I did this?

Thanks,
Nerb

 

[VaughnH]

If you add RO water to reduce the hardness of the water you shouldn't be adding anything to bring the hardness back up. One thing to do is try to find out if there is enough magnesium in your tap water. Some, if not most, water companies provide yearly water quality reports that include magnesium ppm. If there isn't any or just a trace of magnesium, you can add some epsom salts to get enough in the water.

It would probably be best for you to just ignore the pH of the water. GH is good for plants and fish, so ignoring that is a good idea. Water companies add something, usually phosphates, to the water to raise the pH above 7 so copper piping is not eroded by the water. By ignoring pH entirely the worst that happens is that your plants don't do quite as well as they could do, while attempting to regulate pH seems to have caused you to lose your fish. I would prefer somewhat slower growing plants to losing fish.

 

[nerbaneth]

ok, now what about the cloudiness in the water? It could be a bacterial bloom, whatever it is, I believe that it is lowering my DO levels because the fish that remained alive were gasping at the surface for air. will water changes fix this or should I just use some kind of clarification product from petsmart?
Thanks again,
Nerb

P.S. - when is it safe to put my fish back in the tank?

 

[VaughnH]

When there is something wrong with the water, the best idea is to replace the water. I would do a couple of 50+% water changes, back to back, to get rid of most of the "bad" water. Then I would wait a day to see how it looks tomorrow. If it still doesn't look good, I would do two more 50+% water changes. Those four changes should dilute whatever was in the water down to less than 10%. After another day to be sure the water finally looks good, I would slowly acclimate the fish to the new water and put them back. But, if the cloudiness persists, I would then consider dosing the tank with maracyn antibiotic per the package directions. That should kill any bacteria left, and another couple of water changes would get rid of the dead bacteria. Flocculent additives are not considered to be good for the fish, although I have used them for green water without noticing any fish in distress. It is almost always better to be removing stuff from the water and not adding stuff.

 

[nerbaneth]

cool, lots and lots of water changes - I can do that. I bought some seachem clarifier because there isn't any fish in the water. that seemed to help. I am going to use that - do a water change if its not better repeat until it is good, after 4 of those, if my cloudiness is still bad I will get the maracyn antibiotic- hopefully I won't have to.
Thank you everyone so much,
Nerb

 

[Carissa]

Isn't 1 - 2 ppm of nitrites high enough to cause rapid fish death?? It sounds to me like either you had removal or die off of your biological filtration, or a sudden bioload (dead/rotting fish or something) leading to a bacterial bloom and the high nitrites. The high nitrites probably killed your fish by suffocation (nitrite reduces the blood's ability to use oxygen, fish can suffocate quickly and ones that don't die can be permanently damaged, usually they will be hovering near the surface). The bacterial bloom itself should be harmless and will clear up on it's own over a week or so, if that's what it is.

 

[nerbaneth]

I think you are right about the high nitrites.. but what would cause nitrites to shoot up so quickly? My tank is well cycled and at this point. I had stopped testing for nitrites because I had figured if there is some nitrate and my ammonia levels are reading 0ppm then my nitrites should be fine in a cycled tank. And - for all this to happen over night? I suppose my canister could have failed me. there were no dead fish the night before and all the fish were living in harmony with each other.

On a side note, after my water changes and the clarifier, my water is fine and my fish are happy again - there is just less of them

Thanks everyone for your help, I realize this may not be a 'Barr report' acceptable question (it's not really about the plants) but you guys are the ones I believe when you tell me something is wrong

-
Nerb

 

[tedr108]

What model of filter do you have for your 90G tank? My first thought when reading this post was that your filtering system may have been overloaded with ammonia/nitrites because it was underpowered. A hidden dead fish or large snail can cause a fair amount of ammonia. I had a big snail die-off when I cut back on food at one point -- my water smelled pretty strong actually. However, I had a ton of filtering and also did 50% water changes each week, so even with the snail die-off my fish did fine.

I guess another question is what type of water changes you normally do, i.e. how much and how often?

 

[Carissa]

Examine what you did the day before the nitrite spike - did you change anything on the tank? Did you do anything other than a regular feeding? Add any fish? Add anything for that matter? Did you do any tests the week prior to the problem? It's possible that nitrites built up over quite a while and just got high enough to kill at that point. Keep monitoring them for a while, anything above 0 means there's a problem. It's only one of two options - either your bioload got too high or your biological filtration got too low. Add a tsp of salt if you can, a tiny amount of chloride can nearly eliminate nitrite toxicity in case it comes back.

 

[Jeff1192]

I too would be interested to know what you're using for filtration. If your filtration is not sufficient it would definitely be a problem is a large fish died off and went unnoticed. Also, by adding your acid buffer it definitely increases your total dissolved solids in the water and some fish, especially your ram, are sensitive to that.

Jeff

 

[aquabillpers]

I wonder if the higher than normal level of nitrites might not suggest that there was a massive ammonia spike recently. That would account for the overnight fish deaths.

Also, could someone have accidentally put something into the aquarium? I lost some fish when some clown at a party tossed a cigarette into a tank.

Bill

 

[nerbaneth]

my filter is an eheim 2217 (for up to 159gal)
I hadn't done anything the previous day. I fertalized the day before that, but nothing out of the ordinary. The cloudyness in my water was deffinatly algae - or whatever it was my otos LOVED it after the clarifier stuck it together - I realize this might be bad (otos eating clarifier) but I put them in and the next day it(white stuff) was gone/ with 4 very fat otos that are still healthy.
I can't add salt because of the pleco - i think otos are sensitive to it too.
- I don't usually test nitrite because I test ammonia and nitrate at least once a week and a week prior they were normal.
My bioload was wwaay below what a 90 gal can handle. I had 60 inches of fish after they all grew to full size.. at the time I had about 20-30 inches of fish.
I think I answered all your questions.. yell at me if I didn't
Thanks,
Nerb