Fish dying one by one

[romiko]

Hi!

I have an established tank, 280 litre, with about 25 fish,


2 plecos (clown), 2 suckers (both died today), and a range on neons etc.

IA fish died yesterday and 2 days ago another fish!


So 4 fish have died in a week.

I tested the water, ammonia is zero, nitrite is zero and my Nitrate is at around 70mg/l, Guys, I really cannot bring the level down, my tap water is at 50gm/l (Luxembourg).

I have just ordered a Nitrogen and sulphur denitrater, but thats in 4 weeks, what should I do now to stop more fish dying and is it really the nitrates, the thing is, I notice they just die off, bang, no symptons.

 

[romiko]

I also disected one of the fish, and the blood is brown

 

[WILDER]

Brown blood is due to ammonia poisoning, are you sure the fish haven't been showing any signs of stress, like gasping at the top of the tank, or red gills.

 

[romiko]

Hi,


Nothing, gills are fine, the only fishes that go to the top are my Anabantoids to get air as they do naturally, the other fish seem cool as a cucumber, this is odd, I just did a 50% water change, with water that has 40Mg/l nitrate, fighting a losing battle.

They have no diseases, i treat them once a month with a mild antbiotic for prevention, the anabantoid, are chilling and doing their normal thing, it is as if something is murdering them!

I have two shrimps, ghost shrimps which are happy too. Rly odd indeed. Ideas?

I have also iserted denitrifcation resins into the filter for a temp solution, but, I am not sure what it is, I did an ammonia test and the test was yellow, henc eno ammonia or nitrite, temporature is 27.

I must admint (Looks around) the GH of my water is 4 and the KH 3, maybe this is the problem. Now that I did a 50% change, Im sure these two will go up to around 8 -9

 

[WILDER]

Why do you use a mild antibiotic treatment for as if your fish do become ill you won't be able to save them as you have built a tolerance up to the antibiotics, and also it will be destroying your bacteria colony, what's that stuff you put in the filter never heard of it.

 

[romiko]

Just an Ion Exchnage resin bag, I charge it with NaCl then bang it in the filter, I only did this, this evening, I have used it in the past to get rid of the nitrates.


The antibiotics, I have only used it twice, the very first time I put fish in the tank, 2 months ago, and about 3 weeks ago when I introduced new fish.

Thats pretty much that, I used Esha 2000 and Exit.

 

[WILDER]

Did you use the fish to cycle the tank.

 

[romiko]

Did not have to, I had Mature Filter Media from another Tank of mine, which burst. So i bought a new tank and put the fish in emm with the old filter media.

I have two filters, they both been running for around 4 months.

Serious, I tested, the filter before, in a small tank, I added a tiny bit of ammonia hydroxide and it dissapeared after a day. So the bacteria are rather busy.


tested the ammonia and nitrite yesterday and today, not a trace..

 

[WILDER]

With showing no signs of illness, or gasping I would say it could be a bacterial infection, you could try an anti internal bacteria med, have you done quite a few water changes since you used the last med and run black carbon to remove the med out of the tank, do a water change before you add the med.

 

[romiko]

Just did a gh test, it is up to 10 now, you see I have a reverse osmosis unit, which i use to top it up, but tonight, I have filled it with normal tap water, to get it done fast, since the RO is just for GH, usually it is around 22 out of tap, but after I did a 50% water change it shot up from 4 to 10 in the aqaurium, I think My gh was rather loew, and not sure if this had put strain on the fishes..


You see the anabantoids, love water of Gh 7, probably the others like it higher.

Look at the book the suckers that died like a dg 10, so it was 60% lower than recommened. I Am not sure if dg is similar to Ph Logarithms, liek ph 7 is 1000 times more than ph6.

So ph 7 is 10^6 x more than 5 (1000000 more)

is dg also like a logarithm?

 

[WILDER]

Any test result with a big change in it can kill fish, so it could be.

 

[romiko]

made a slight mistake


7 is 10 x more than 6
7 is 100 x more than 5
7 is 1000 x more than 4
10^4
10^5 and so on

 

[romiko]

I don't know, coz the dg has been around 4 for two months, so, no other change,


I was doing a 10% water change every week, with water that had 50mg/l nitrate. it could be that the nitrates built up to a unsustainable level.


Only way to find out is illimibating each variable one by one, gonna be costly!

Will let u know how the fish do over the next few weeks.

 

[WILDER]

Good luck anyway, can only advise fishkeepers no there fish the best.

 

[blue_ram]

I tested the water, ammonia is zero, nitrite is zero and my Nitrate is at around 70mg/l, Guys, I really cannot bring the level down, my tap water is at 50gm/l (Luxembourg).

I have just ordered a Nitrogen and sulphur denitrater, but thats in 4 weeks, what should I do now to stop more fish dying and is it really the nitrates, the thing is, I notice they just die off, bang, no symptons.

Nitrate itself doesn't kill the fish, as it's pretty much non-toxic by itself. Nitrate is only an indicator of level of organic pollution. Unless there are other organic pollutants in the water, it's unlikely the cause of death. I wouldn't mess with denitrator. If something goes wrong, it will dump hydrogen sulfide into the tank, killing all fish. I'm not sure if the new denitrators have improved or not, but you might want to do some research on it.

I also disected one of the fish, and the blood is brown

Brown blood is usually a sign of nitrite poisoning. But since your nitrite reading is zero, either your test kit is too old, or it's something else that's oxidizing the blood. In any case try adding SMALL amount of salt (2 tables spoon) to your aquarium.

I must admint (Looks around) the GH of my water is 4 and the KH 3, maybe this is the problem. Now that I did a 50% change, Im sure these two will go up to around 8 -9

Fish won't die from Gh shock, only pH shock. If pH rises (or worse, falls) significantly, it could kill the fish. But you'll see the symptoms immediately. If it's been several hours, and fish looks fine, then it's not the Gh/pH problem.

What other stuff do you add to your tank? Sounds like you got a complicated setup. I don't like complicated setup, because a small mistake could be disasterous.