HELP! Nitrates are high and fish are dying.


New member
My nitrates are high and my fish are dying. I have done a water change but that didnt seem to help. What else can I do?
Do about 25% a day, but like BJ said, we need to know more about your system. How long has it been running? What livestock? Water parameters. How fast did you add livestock in. what are you dosing......etc
how are your fish dieing? symptoms, what is dead, what isn't, corals, other things in the tank?

how long has the tank been set up
what are the numbers for ammonia, nitrite, nitrate, PH, temp?

when he means flow, yes: what kind... powerheads, heaters, what type of skimmer...

the standard questions.
One anemone and 2 fish died. My ph, alk, nitrite, ammonia are all fine and temp is at 84. I just seems to be my nitrate. My tank has been up for 2 1/2 months. I have a coralife super skimmer, ehiem filter, and a powerhead.
fine means nothing: NUMBERS please.
and what size tank.
2 and a half months is too young to house an anemone, IMO,
what kind of fish died?
whats left?
what type of powerhead?
and 84 is a little on the high side: slowly try to lower it to 80ish
magnesium if you have it.

when was the tank set up?
When did the cycle complete?
what type of lighting?
how many fish and when were they added along with the size of each?
If you don't have a sump what other type of filtration do you have? Hang on back? Do you have a skimmer and what type?

Are you dosing anything?
What type of substrate?
How often do you do water changes and how much?

If you could provide that information chances are there are dozens of people who can help you.


IMO 84 deg is defin alittle high. Drop it down to 79 to 81 deg.

Also post some test results!..

How often were you doing your water changes before the die off?
How often do you clean your filter & skimmer-> Whats your tank maintenance regimen?
ok follow this guide and you should get through it...

1) 30% water changes daily
2) take that anemone, corals,inverts and clown out and take it back or give it someone who can care for it for the meantime
3) get a sump
4) Start the cycle again...

you dived into this hoby to fast, anemones nead excellent water conditions and your tank nead to be around 8 months old atleast... what type of lighting are you running (who wants to be floresent 30 watt tubes?)
ummm, who said he had a clown, the anem is dead... huh? and a sump isn't needed for anything... we need answers to the questions. There would be no need to cycle again. the nitrates are telling us something, but unless he posts parameters that have been asked for, then we can't even begin to tell him whats wrong, other than the tanks too young for an anemone.
55 gallon, cycle completed about a months ago, the fish that died was a gobie and a clown tang they were added about two weeks ago. I have a canister filter. temp is 84, sal. is 1.024, alk 300(says ideal), Nitrite 0, nitrate 160(says unsafe), Amm 0, ph 8.3
you are most likely overfeeding if your nitrates are that high. Also if you dont have much live rock that can cause your nitrates to be slow in comming down. If you can add some macro algae to the tank that may help too in lowering it, but even once you get it down, you need to fix the cause of it being that high in the first place. If you are using tap water that may be part of the problem. Some water has high nitrates.
it also sounds like too much, too soon.
do you have any fish left? a tang, IMO is too big for a tank under 90 gallons, especially a clown tang, as they get well over a foot in nature. I know, I'm horrible... Nemo can tell ya!!! I shoot down all sorts of fish stocking ideas.

in a 55 gallon tank that is less than 3 months old, you REALLY need to slow down. The nitrates being that high may just be from having HUGE fish in there that need HUGE places and have HUGE poo!!!!

tanks under 6 months old are too unsteady for ANY anemone.

I'd like a full stocking list, because I get the feeling that there are just too many fish in there, causing a HUGE bioload, creating nitrates to skyrocket, just like that.
What brand test kits are you using ? Looks to me like your tank is not ready for fish yet ?

In this hobby you've got to take things slow. You've got to know your water perams are before you add fish.

Patience....... Patience......... you will be rewarded........ :)
ok... I'm sorry to say this, but good.

do water changes, bring the nitrates back down. consider this a VERY COSTLY LESSON!!!

don't add another fish until the nitrates can hold themselves steady @ less than 30-preferably less than 20. Feed the clown once every couple a days, and only enough for it to eat in 5 minutes. at the most, 3x a week.

the largest fish for a 55 should be a dwarf angel. tangs get too big, as do most other fish. An anemone will need alot of light, which you never did state what you had. clowns do not need an anemone to live: look at other corals, such as frogspawn, hammers, colts, things like that... if the clown wants to host, it can host in those.

do not add more than one fish every two weeks. Maximum, one 'medium' sized fish-a dwarf angel or smaller
and then, a few small fish-your clown, and MAYBE 4 other fish.

for now, lots of water changes are in your future. Its too bad that you had to learn this at the expense of an anemone that can live 100's of years, and two fish that can live to be in thier teens...