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Pathogen or toxin? And remedy.

idris

idris

Member
Joined
3 Jan 2011
Messages
816
Location
Herts
I'm having problems with continued fish deaths.
In two months I've lost 8 Dwarf Gouramis, 3 (possibly 4) Kilis, at least 6 Neons. I only ocasionally see my Ottos but I've seen no corpses. My Amano shrimp seem very happy and have got more active recently. My Assasins seem to have bread and I've seen young (small) snails out and about.

Initially I thought the problem was pathogenic, being brought into the tank by new Gouramis. I don't think it's iridovirus as it's not just Gouramis that are dying and as I understand it iridovirus shouldn't jump species.
I've only managed to get to a couple of dead gouramis before they were well eaten - I can see no signs of damage to fins, scales, gills, or eyes: no obvious parasites, fungus, fin rot, sores etc. The only visible signs I've seen on the fish are degredation of the whiskers on one of the Gouramis - they were shortened, the colouring was slightly uneven, and it looked like one of them was splitting. (My guess is that the outer skin was dying and breaking away.) When the fish do display problems, they are breathing heavily, sometimes at the surface, other times they are lying against leaves or wood deeper in the tank. Sometimes they have also been slightly clamped.

Most recently, after about three weeks with no deaths, I lost one Gourami the day after a water change, another the next day, which I think points to toxins in the water being added.
From what I've read, toxins like chlorine and chloramine should kill quite quickly, which concurs. But then I've had another Gourami looking like it's about to die last night (I have yet to find a corpse, but I'm pretty sure I will) - about 8 days after this water change,which seems to suggest the problem is not chlorine/chloramine. The water is treated for these anyway.
Ammonia, nitrite and nitrate levels seem ok, based on my (notoriously unreiable) test kit.

My plants seem to be fine, with the exception of GDA on the glass and short filamental green algae on plant leaves.

My shrimp seem fine so it's not copper.
I don't use CO2 or ferts, so that's not an issue.
As I don't vac my substrate (Akadama) and as I've seen alerts about H2S I briefly wondered whether that's likely to be a problem, but the tank smells normal so I don't think that's the issue.

Which all leads me to think there is some other toxin entering the tank.
I have replaced all the tubes I use to do water changes with, just in case they've somehow been contaminated.

Does this make sense? And short of switching to RO water (and I can't justify that) what is my next best option.
 
Here on local forums people advised us that the water company is using Aluminium sulfate and could cause issues if the water is not treated prior water change. I'm using only mineralized RO water and I haven't got any issues in the past two years with fish deaths related to water change.
 
Interesting, usually shrimp goes first when something is wrong with the water. Any toxin would kill them much faster than your fish. Maybe you are not hitting water parameters for Gourami if they are wild caught. You should probably research there.

Here from fish base:

Temperature

72 - 82°F (22 - 27°C)

pH Range

Wild fish tend to inhabit environments containing soft, acidic water. The tank-bred fish are more adaptable and can normally be maintained anywhere within the range 6.0 - 7.5.
 
I don't think aluminium has been used in the UK for some time. (But someone will doubtless now better than me.)

I have no idea whether the fish are wild or tank bread. We are in a V hard water area. Temp and pH are at the upper end for Gouramis, but that wouldn't account for the Kilis and Neons going at the same time.
 
It could be something as simple as keeping softwater fish in very hard water, especially if water hardness/pH is fluctuating a lot with water changes. Also, I think I'm right in saying that iridovirus has been shown to transmit to other species sometimes. Aggression could also be playing a factor, as DGs can get pretty nasty towards each other and other colourful fish.

http://www.seriouslyfish.com/profile.ph ... lius&id=82

I would probably think hard about revising your stocking plans to more suitable and less disease-prone species.
 
Gouramis can certainly be little sods. In terms of ruling out aggression as a factor it would worth knowing what size tank you have. I'm interested because I was considering haveing a similar amount of DGs in a new tank I'm planning and from past experience potential aggression has me a little worried.
 
I thought I read recently that the general quality of Dwarf Gourami's for sale in LFS was pretty poor. This wouldn't apply to the Killi's and Neon's that are mentioned by the OP.

Just food for thought...

Andy
 
GH and pH have always seemed pretty stable. Water changes are only 10% weekly (though I'm a little warey of doing them at the moment.)
The male DGs went in the tank about 5 months ago IIRC. They were fine, though aggressive towards eachother, which is why I bought 3 females, which all died within a few weeks. I replaced them with three more, and one (or two, I forget) died in about a week. The LFS I got them from said it was aggression ... but they would, wouldn't they. Just in case I bought three more from a different LFS. Since then I've lost two of the original males and am down to two females.

The tank is 250l, (4ft wide, 2ft6 tall and 1ft deep) with lots of places to hide. (I think the max number of DGs has been 7 at any one time.)

All in all, I'm not convinced it's harrasment.
Poor quality DGs is possibly a factor, but that wouldn't account for the male DGs lasting 5 months and then dying, or the 12 Neons lasting nearly a year and then half of them dying in about a week.

I'm pretty convinced it's (primarily) pathogenic of toxicity, probably toxicity, but I'm baffled in terms of what it is, and how to deal with it.
 
To be honest it sounds to me like it could just be a combo of unsuitable water conditions, low quality stock, aggression and possibly disease. Any one of these can leave the fish in poor condition and it wouldn't take much of any of the others to push them over the edge. I don't see that there needs to be any additional mystery explanation.

If it were me, I'd stop trying to over-think things and change my stocking for more suitable fish.
 
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