Diagnosing fish death

[idris]

Over night I've lost 2 Dwarf Blue Rainbows. I know dwarf varieties are usully weaker, and if it was just one I wouldn't worry, but as I lost two together it seems logical to think they're connected.

They've been in the tank for several moths and both were males.
Aside from the dead fish having been nibbled, neither were mis-shaped in any obvious way.
There was some blackeing around their mouths, but whilst I'm pretty sure they weren't like that when they were alive I can't say for suere if that was a result of decomposition.
(There are 3 remaining females and one male.)

Eveything has seemed healthy recently.
Ammonia levels are zero (Well, zero-ish: the API test kit solution appears to be between 0 and the next colour on the chart, but test solutions are notoriously inacurate and fresh tap water produces almost exactly the same coloured test soloution.)
Nitrites are zero.
Nitrates are about 10ppm
I did a water change two days ago (20% rather than the usual 10%) and moved a couple of plants about 10 days ago, but those are the only recent changes.

Everything else looks normal.
Any thoughts?

 

[dw1305]

Hi all,
Sounds like it may be oxygen related, when deaths occur over-night that is always my first thought. I think this is a tank without added CO2? so if it was an O2/CO2 ratio problem you would need a combination of a very large plant mass and relatively water turn over. I think Rainbows have quite a high oxygen requirement, but I don't think Melanotaenia praecoxis any more sensitive than the other Rainbow fish (it isn't a dwarf form of another species, it is just a smaller species).

Has there been any water mains work near to your house? if there has, I would suspect chloramine poisoning, this trickles ammonia into the tank and the NH3 conversion then depletes the water of oxygen.

cheers Darrel

 

[idris]

Correct, there is no added CO2.
I'm not aware of the water board doing anything locally. I dechlorinate all water going into the tank, but I guess if there are unusually high levels I may not be adding sufficient dechlorinator.
I'd say biomass is moderate and although flow distribution needs improving, flow level isn't too bad. (EX1200 for 220L).

 

[idris]

Another one down over night. (A female.)

If it is an O2 deficiency, would it be any use to put an air stone in?

I don't know if it's related but I've spotted a small bit of damage to a gill plate on one of the Dwarf Gouramis. Though this could be related to bullying by one of the others.

 

[dw1305]

Hi all,

Another one down over night. (A female.) If it is an O2 deficiency, would it be any use to put an air stone in?

Sorry to hear this, an air-stone is a good idea. What ever the cause I'd try and do a large water change with non-tap water if you can? Low O2 wouldn't effect the Gourami, they are Anabantoid fish and can use atmospheric O2, although they would still be damaged by any NH3.

We had an absolute spate of these unexplained deaths last year after the big freeze (on Plecoplanet), and I'm pretty sure these were chloramine related, as the water companies added it to supplies that had been compromised by broken pipes. You need a conditioner like Prime or Amquel that specifically deals with chloramine.

cheers Darrel

 

[idris]

I've just spoken to Veolia (our water supplier) and have been told (indirectly) by their water quality team that they don't use chloramine in our area at all.

I've now spotted one of my Neons occasionally rubbing aginst leaves. And it's possible one of my Kilis may be slightly clamped.

I'm in the process of doing a 25% water change, but getting 50L of tap water up to 25c is a slow process. Kettles and saucepans are on the go.
I'm not filled with confidence as it's possible that a water change may have started the whole problem. I can think of no way any contaminants could have entered the tank. So I'm still baffled and increasingly worried.

 

[idris]

Another Rainbow down over night.
Some of the Neons are very flicky.
If Ottos or Amanos have died, odds are I wouldn't find them.

Had the water tested at LFS (MA) and they say he water is fine, and confirmed that chloramine is not a consideration. Their only suggestion is that I've been running the temperature too low.

[Last edited 09/11/11 @ 14:33 - Reason for editing - missing Kili turned up.]

 

[idris]

And then there was one

 

[dw1305]

Hi all,

And then there was one

I'm really sorry to hear this, this was why I stopped keeping fish the first time, in my case it was because I didn't understand what I was doing, and various people gave my advice that led to me repeatedly killing my own fish. Fortunately thinks have moved on since then, both personally and for the hobby.

In your case I'm sure it must be something toxic in the water. Unless you've sprayed the dog for fleas, or fumigated the carpet etc in the same room, it must have come in with the tap water.

Had the water tested at LFS (MA) and they say he water is fine

They can't really tell you this, to get a meaningful analysis of your tank water you would need the Environment Agency to run it through their analytical lab. If your water was full of aquarium salt, or you had huge levels of ammonia or nitrite, they could detect them, but not otherwise.

and confirmed that chloramine is not a consideration.

They can't test for chloramine either, but this is exactly what happened in the winter, a variety of "water tests" and denials, followed by an admission that "emergency levels" of chlorination had been used.

Veolia say

A very small part of our distribution network, notably around North Luton, does receive water that has been treated with Chloramin rather than chlorine. This does not change the high quality of your water but could be of interest if you keep fish, for example. If you would like us to confirm whether your water has been treated with Chloramin, please send your request through 'Ask a Question' and we will be happy to help.

from <https://threevalleys.custhelp.com/c...r/std_adp.php?p_faqid=72&p_created=1224868389>, but a lot more companies are using chlormamine either routinely or in an emergency.

This is Scottish Water <http://www.scottishwater.co.uk/port...SWE_PGE_NEWS/INFO_WAT_QUAL/SW Factsheet 6.pdf> and Thames Water (under Ammoniation) <http://www.thameswater.co.uk/cps/rde/xchg/corp/hs.xsl/2915.htm>

cheers Darrel

 

[idris]

Thanks Darrel.
I'm aware of the limits of what the LFS can test for, and AFAIK their comments on Chloramine were not the result of a test, but rather local knowledge. Very interesting info about Luton water though, as it is contradictory to what Veolia told me. And we live just south of Luton.

Thankfully I have rarely lost fish - the only time I've lost more than one agimg fish was when a whole tank was wiped out after introducing two new fish. But that was entirely different to the current problem. Generally, what ever I've been doing has been right enough to not kill fish.

 

[dw1305]

Hi all,

Thankfully I have rarely lost fish - the only time I've lost more than one agimg fish was when a whole tank was wiped out after introducing two new fish. But that was entirely different to the current problem. Generally, what ever I've been doing has been right enough to not kill fish.

I'm pretty sure this isn't something you have done and I think it is a tap water issue. If the Veolia site has a "schedule of works" for water main removal/repair it might tell you whether they are doing any water main restoration work in your area.

In W. Bristol the water is usually quite good quality (comes from the Chew Valley Lakes), but hard. I know some of the Bristol Plec breeders quite well, and they were cutting their RO with about 1/4 tap to give them about 4dKH/GH and breeding all sorts of stuff. Even this small volume led to fish deaths during the water mains work. Out of the 2 I know best, one was so upset by the whole business that he has scaled right down and is thinking of giving up, and the other one now runs his 1/4 tap through an HMA filter.

cheers Darrel

 

[idris]

If the Veolia site has a "schedule of works" for water main removal/repair it might tell you whether they are doing any water main restoration work in your area.l

They do. It doesn't. We may never know, but it'll take a lot more than this to make me give up.

Thanks for the help anyway.
Any thoughts on why it's just killed one species. (The dominant / strongest male is currently the last one swimming.) My guess is that more fish in my tank may have been effected, but that the Rainbows are either weaker as a species, orthat in their weaken state they just got hit by an infection that they are more susceptible to than the other species in the tank.

And how long would you recommend leaving before restocking?

 

[dw1305]

Hi all,

Any thoughts on why it's just killed one species...My guess is that more fish in my tank may have been effected, but that the Rainbows are either weaker as a species, or that in their weaken state they just got hit by an infection that they are more susceptible to than the other species in the tank.

Probably they have a higher oxygen demand than the other fish and whatever has caused your problem has stressed them either directly or indirectly.

Usually what we call "difficult fish" are fish with a very limited range of conditions that they encounter in nature and little adaptability. Often if we can fulfil this requirement they stop being "difficult". You could think of a fish like Betta channoides it needs live food and very good quality, soft, acid water, without much water movement, but it doesn't bother the fish if oxygen levels are low, because it has a labyrinth organ and lives in oxygen depleted swamps in the wild.

A rheophilic like a Hill stream loach (Sewellia lineolata) is totally the opposite it wouldn't be much bothered by water hardness, but would have a very high oxygen requirement and specialised dietary requirements etc.

And how long would you recommend leaving before restocking?

No idea with that one, you would really need to know if it is an on-going water issue or a one off. I've always used rain-water, it may not be perfect but I've never had any problems with it. If I was forced to use our tap water I would keep different fish (basically "Lake Malawi" comes out of the tap, hard but low in most pollutants) and use an HMA filter.

cheers Darrel

 

[idris]

A VERY interesting development this evening.

I just made myself a cup of tea and noticed it tasted odd. Not a chlorine taste, and one I can't describe. So I sniffed the water still in the kettle and it smelt the same.
We have a kitchen tap with built in drinking water filter (the tank is filled with unfiltered water) and the unfiltered water had the same smell, and possibly stronger.

I drink a lot of tea and I'm pretty sure I would have noticed the taste before, so I wonder whether there has been a slow increase in something like chloramin that the fish have fallen foul of before it reached a level where it could be tasted.

The other possible cause that has just occured to me is that there are a couple of new houses being built in our road. I'm sure it shouldn't happen, but I wonder whether something has been back-washed into the mains water.

 

[dw1305]

Hi all,

The other possible cause that has just occured to me is that there are a couple of new houses being built in our road.

I'm fairly sure this is it, this is the water main work, where the new houses are being tapped into the water main.
My suspicion would be that it isn't something that has accidently got into the water, but a compound that has been deliberately added as a disinfectant, and that should have been flushed out subsequently.

I found this <http://www.anglianwater.co.uk/_assets/media/DS_Disinfection_Leaf_4PP_6-7-09.pdf>

That should mean the water will return to normal fairly quickly.

cheers Darrel

 

[idris]

Interesting ... ish.

I've spoken to one of Veolia's water quality team at length on a couple of occasions over the lasr 48hrs and he was very helpful (and not at all defensive or evasive as I expect from companies these days so I'm inclined to take what he said in good faith). In that perios he has looked into what is going on in our area.

There have been no significant water works in our area recently or leaks.

Although they do buy in water from another company which does use chloramine, and there is a chance that this can rarely make up some of our water, this has not been the case recently. So chloramine is out of the equqation.

I asked about the possible impact of local building work. His thoughts were that this is not real consideration as any contaminants would be expected to pass into the waste water system. For them to enter the mains water supply they would have to be pumped back into the water mains at considerable pressure. So not a real posibility.

As for the odd taste, he attributed this to the non food grade pipes for our dishwasher which are connected very closely to our kitchen taps. Fluctuations in chlorine levels can lead to reactions with the phenols in such pipes and result in the water tasting odd. (We tested this by isolating this pipework, which cured the taste problem.) Although this can be the result of elevated chlorine levels, the chlorine treatments in our area have not been aabove "normal" levels recently.

So no solution at the moment.
And despite having had a few deaths without any further deaths, and the last of the Rainbows still hanging in there, unfortunately one of the Kilis sucumbed today (and although I can see the dead fish, there's no way I can get to it without dismantling half the hardscaping in the tank).