Death with discoloured gills

[NULL]

Any intelligent guesses what this could be?
Test results:
NH4 < 0.25 mg/L
NO2 0-0.3 mg/L
NO3 12.5 mg/L
PO4 0.5 mg/L
pH 7.4-7.6
KH 3
http://hem.bredband.net/andersdoverud/Misc/Amanogills.jpg

[Frank]

When I see the break in the neck this shrimp wanted to molt and died during the process.
Discoloration is normal when they are dead.

[NULL]

Thanks for your reply. :)
The discolouring appeared before death.
Can the KH value be a clue to if it is a molting problem?

[NULL]

I guess that the gills are somewhat clogged, and that it doesn't have to have anything do with the death.
I had two amano who molded the day after, and they had brown gills too, so back to that it maybe is the KH...

Old shell
http://hem.bredband.net/andersdoverud/Misc/IMG_7948.JPG

Gill deposit
http://hem.bredband.net/andersdoverud/Misc/IMG_7965.jpg

[TitoC]

Hi

If you can see brown gills like that in several shrimp it is surely not normal. In aquaculture shrimp this is usually caused by fouling of the gills in dirty water in the ponds. (it's the animals response to the bacteria/fungus/protozoa by melanizing the tissues in an attempt to keep the bacteria from spreading into the body. Of course this reduces the oxygen uptake with suffocation as a consequence)

BUT, as it is a Caridina japonica here, which I'm guessing comes from a very clean and stable tank, I find it hard to believe you somehow stressed them in a way their defense was compromized enough for opportunistic pathogens to kick in.

Still, it is possible, for instance if they are already very old and they don't need much to be put down.

The break in the neck could be a normal effect of the shrimp being dead and laying on the dry (they fall apart fast after they die), but it is true that if the shrimp was close to the time of molting, the extra layer of cuticula on the gills could lead to suffocation in a shrimp that was already weak (to weak to kick of the skin).
Indeed, a shrimp which does not get enough oxygen in its blood turns white (milky color of the tail, as you can see in the picture). The question is, did this happen as a result of its death (so after it stopped breathing), or was it a sign of the cause of death...

If you know a good veterinarian, next time you have a shrimp like this you could take a look under the microscope of the gills, preferably before the shrimp is dead. Samples can be send for histology to see if its really bacteria.
Maybe not worth it for Caridina's, unless you are breeding a lot of them.

Still, with anamnesis, we could still identify the problem. My most important questions are:
- are these old shrimp?
- did you stress them somehow? (big water change? any products you used? the fact you had several shrimp molting around the same time could indicate a repons to a big change in the environment)
- how do the gills look like on the other ones now?
(how many shrimp do you have in the tank)

Hope this helped a bit.
When I get to work tomorrow, I can look up a more literature.

Mat

[southerndesert]

One of the symptoms of Nitrite poisoning in fish is brown gills..... Could shrimp be the same in that respect?

Bill

[TitoC]

This guy is one of the biggest authorities when it comes to diagnosis of disease in farmed shrimp, and probably the biggest one in histopathology.

I include a few pictures from the manual he composed back in 1996. I hope you guys help with not getting me in trouble for reproducing this copyright work ;)

I will make it up to him by saying you can order it here: https://www.was.org/shopping/shopexd.asp?ID=48

It was made with tax money anyway :)

1126

1127

1128

1129



Notice any resemblance with the Caridina japonica?

Anyway, all these conditions are basically caused by a deterioration in the environment and the defence capabilities of the shrimp.

I don't know if this is an option for this case, NULL?

[TitoC]

this is what fouling would look like in close up

[NULL]

It is not often the answers are more extensive than expected, I am really thankful for all the help. =)

“If you can see brown gills like that in several shrimp it is surely not normal.”
Yes, it was several who had it. Then it first struck I had 20 amanos, a guess is that approximately half had discoloured gills, but I am quite unsure about it.

“…if they are already very old…”
This is the first of a couple of diffuse signs that is making me wonder.
My shrimps are mixed of moderately old, and extremely old, so I can’t say for sure...

“The break in the neck could be a normal effect of the shrimp being dead and laying…"
Several of the dead shrimps had that type of break as in the picture, just as big so I can’t decide if it is a molting problem, or just decaying.

“Indeed, a shrimp which does not get enough oxygen in its blood turns white (milky color of the tail, as you can see in the picture). The question is, did this happen as a result of its death (so after it stopped breathing), or was it a sign of the cause of death...”
Agree, so that is another thing which complicates the question if the discoloured gills have anything to do with the deaths.

No, we don’t have a good fish veterinarian in 200km, and it costs 100$ for a check by the state institute “Statens Veterinärmedicinska Anstalt”, and I guess that they are no good with shrimps anyway...

I do weekly water change 30-40%, due to the small size of the temporary tank.
I have now only three males and one female left. After the last molting of two of the males, the last discoloured went.
I have a hobby microscope, pity I didn’t think of looking at the gills with it…


Update:
The two last molded(guessing), have missing walking legs, and one have a bigger white leg. So the molding could have been difficult for them to preform...

[TitoC]

So if i understand correctly, they are in a small tank and some of them have damages? This sounds like they are not in optimal conditions. Even with water changes, there will be a lot of fluctuations in the water parameters...

Missing legs indicate a serious problem.
This can only be due to bad housing (did you put gravel, or is it bare-bottom?) or due to fighting (is there anything else than shrimp in there?).

The adult Caridina japonica in my community tank also seem to fight sometimes, especially the females, over the best hide-outs and food. Possibly there is a fungus or a bacterium taking advantage of this situation. The wounds will allow entry of opportunistic pathogens if the water is 'dirty' and the bacteria will spread into the body, accumulating in the gills and killing the shrimp finally when they try to molt.

My suggestion is to keep them in a suitable tank, although it is more post-mortem now...

Mat

PS. From Sweden he. In Uppsala there is a Professor called Kenneth Söderhäll.

(He works at the Department of Comparative Physiology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18A, S-752 36 Uppsala, Sweden.)

He works on the defence system of crayfish (mmm Kräftor:)) and shrimp. Who knows, maybe he or somebody of his lab will be interested/willing to see what the cause is...

[NULL]

I have often seen that the females can be food-aggressive and scare the males of their food, but I have never seen any damage because if it. I have only had one female in the small tank. And I moved their favourite hide-out with them to the new tank.
After the last death, I added one bigger calcium based rock, and added liquid KH+...KH now at 8.

I guess this is so far we can get, it is hard to get any sure answers at this moment, thanks for all help again.

More pictures:
The tank with old, cleaned "coal-stone"-sand bottom-filter, Left: Hide-out, Right: New stone:
http://hem.bredband.net/andersdoverud/Misc/Akvarium_20L_2008-01-17.jpg

Early discoloured gills:
http://hem.bredband.net/andersdoverud/Misc/Caridina_japonica_2007-11-28_01.jpg

Break in the neck on dead one:
http://hem.bredband.net/andersdoverud/Misc/Caridina_japonica_2007-12-01_07.jpg



One of the symptoms of Nitrite poisoning in fish is brown gills..... Could shrimp be the same in that respect?

Bill

I don't think so, my NO2 levels, whenever I tested, has been low.

[TitoC]

yeah, that tank normally should be just fine...
I was imagining a small plastic temporary tank.

remarkable:
- presence of eggs is a sign they were in a good shape before. (it looks like a fresh batch, was it laid after she got the brown gills?)
- they still behave normally, eating and preening
- skin is completely spotless, and appendages are intact
- all shrimp seem to have a similar level of coloration in the gills
- the color is too light to be melanization if you ask me
- their bodies seem already milky whitish (so oxygen up-take is down)
- that last dead shrimp does look like it was about to molt

my guess is that this condition is metabolic/toxic
some metal might be getting accumulated in the gills

can you check for any source of metal in this tank?

Any rusting metal, a copper wire, a broken mercury thermometer etc.?

What are those 2 sticks in the left corner where the healthy looking shrimp is sitting?

And perhaps those rocks also contain too much of a certain metal...

Could be that I'm off, but the gills are the classic site for (heavy) metals to accumulate... (the attachment 1128 in my previous mail is of iron salt precipitate)

Mat

[NULL]

Oxygen in the water should be fine, I’m a catfish fan too, so most of my tanks have much more speed in them than usual. Look at the picture in the right corner, you should be able to see the waves from the pump, I didn’t want to reduce the flow, so I had to turn the output straight on to the opposite side. The bigger Monosolenium tenerum(and the filamentous algae on it) on the left, have that shape due to the flow.

The last picture of the dead shrimp is an old one, and I have no clue how long it have been dead in the picture.

I have now moved the last two remaining shrimps to another quarantine tank, just so I have a chance to get an answer to the problem.
They now doesn’t have any bottom material, a used sponge filter from another tank with 250L/h pump, and the old rocks, hide-out, flame moss and some of the Monosolenium tenerum.

I have looked through the old bottom material, haven’t found anything.

The two sticks were wooden flower holding sticks.

The rocks known as “FaxeKalk” are common in Swedish aquarium shops. It’s coral-calcium(limestone) rock from Faxe in Denmark. We have the same stuff in Sweden, so I’m not sure it’s “original”. =)
On german: http://de.wikipedia.org/wiki/Faxekalk

[NULL]

Last dead shrimp:
http://hem.bredband.net/andersdoverud/Misc/Caridina_japonica_2008-01-22_02.jpg
http://hem.bredband.net/andersdoverud/Misc/Caridina_japonica_2008-01-22_13.jpg
http://hem.bredband.net/andersdoverud/Misc/Caridina_japonica_2008-01-22_17.jpg

[TitoC]

The possible explanations are running out. If there was nothing rusting in the tank, the only thing that could be leaching metals are the rocks. However, you had a low GH in the tank, right?
I forgot to suggest to add active carbon to the filter, to if the symptoms reduce. That would be good prove for (heavy) metals.

But, what's up with the gill chamber on the right side in that last picture? That fluffy white stuff reminds me of fungus! Could you take a look with a microscope at that?

[NULL]

Well, GH is always 5-6 in our water, so I don't measure it, only kH.

The two last dead shrimps had one gill lid lose. The first slipped my attention somehow… On the last I noticed it, it did looked like fungus, so I took some photos at it and published it fast. In microscope it just looked like oval cells, I didn't see any structure in the sample, as far as I can interpret without any training in it.
The lid was somewhat soft, I don't know how hard they are usually.

I have a hunch that something happen when I added “Sera kH+”. I added it of course in arrears, but both molting and death seems to be the direct result somehow by my instinct…
(When I started to suspect too low kH=3(or 53,4ppm CaCO3). I raised kH by max 2 per day, to kH=8(or 142,4ppm CaCO3) with “Sera kH-plus”.)

I went through the thread and noticed a mistake by me.
The bottom where silicon based, not coal stone based, a mix up. But if the remaining shrimps survive without it, I’ll throw it away of course.

[TitoC]

Did it look something like this?

But wait, you added the KH+ only later right? Not at the start of the problem?

[TitoC]

or like this?

[TitoC]

This one is known in farmed shrimp, Fusarium, where it is an opportunistic pathogen which kills older shrimp (broodstock). It is a possibility in your tank, but it would imply your shrimp were weakened by something else.
The are rather easy to identify by the canoe-shape of the spores.

[TitoC]

but you say the ones you saw were oval, no?

[NULL]

Yes, oval.
But on your pictures with oval ones you have those branch-like things, my sample was just lots of oval cells in a mix...

[TitoC]

...could still be a post-mortem overgrow with a non-parasitic fungus...

But in any case, Japonica's don't suffer from fungal disease without prior infection with a primary pathogen or detrimental environmental conditions to depress their defence system.

Could it still be that you had pH fluctuations due to the low KH?

With the rather high pH this would have allowed high enough ammonia peaks to be toxic, and since your tank is rather bare and the KH low, there is not much buffer available.
This would however require:

- substantial feeding
- limited filtration capacity (not much substrate+bacteria)

Is this possible you think?
Ammonia is just one of the few things I know from experience that can get Japonica's to die...

[NULL]

I rarely measure the pH, of laziness, and because my pH haven't surprised me yet.
So in this case I don’t know the pH, guessing between 7-8 as always. =)
(I’m in fact wondering why the pH stays so stable with so low gH…)

“Substantial feeding”, possibly, but not anything deliberate…

“Limited filtration capacity (not much substrate+bacteria)”, my bottom filter was approx 1/6-1/8 of the tank’s volume, and it was half dirty when I looked for Cu.
But, this far the remaining shrimps are still alive in the new tank, so my strongest guess must be NH4 despite of my test result…
("NH4 < 0.25 mg/L" was uncoloured on the test reference chart)