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If anyone else has any other explanation I'd be glad to hear it.
This is in 2 different tanks, 29g and 55g. Unfortantely I contaminated my 29g somehow. Not sure how that happened.
Water parameters:
Ph: 7.8-8.0
gh: ~6
kh: ~12
nitrite/ammonia:0
nitrate: 15-20
Had a full water test done and they said levels are ok but my water is higher than normal in phosphate, silicate, and iron. Anyone know the safe levels for iron in aquarium water?

Fish lost so far without a known reason: 4congo tetras, 7emperor tetras, 2rams, 2 threadfins, 6black neons
Fish that are not getting sick: gourami, yoyo loaches, panda cory, otos, farlowella, and the plecos.
I bought emperor tetras which started dying without reason or showing any symptoms. I have 2 left and few days ago I woke up to 3 dead congos and 4 dead black neons in the other tank. The next day another dead congo and a dead threadfin. Today the last of the black neons are dead. I've only seen 2 fish show any symptoms at all. An emperor started to fall sideways and sink to the bottom, lost it's color, hid in the plants for a few hours, then was found dead. The last congo to die was hiding in the plants all day and not schooling with the others like usual. Otherwise the congo and the other fish didn't even show faded color or any symptoms. Sometimes I'd be watching the tank and see nothing wrong. Walk out of the room for a drink or food and come back to a dead fish. Anyone have any ideas what to do?

With losing alot of fish it might be a bacteria infection did the fish darken in colour, have you ever kept neon tetras with the fish.

http://freshaquarium.about.com/cs/disease/p/neondisease.htm

Last edited by Lindy at 11-Apr-2005 06:47

Hmm. This doesn't sound like the usual progression of NTD.

Neon Tetra Disease (named because it was first described in Neons, but can affect other fishes too) is caused by a particularly insidious parasite called Plistophora hyphessobyconis. This is one of a group of protozoans called Microsporidia, and these are insidious parasites that are extremely difficult to eliminate once established. While a protozoan such as Ichthyophthirius (the causative organism for White Spot) has a free-swimming larval stage that can be destroyed with ease by medication, NTD is transmitted by penetration of the gut wall by parasites inhabiting dead tissue from the previous victim (usual infection route is the eating of the flesh of an infected dead fish). These parasites then radiate out to other tissues, and as the disease progresses, they cause muscle degeneration that shows up as white patches that are very distinctive, particularly on a highly coloured fish such as a Neon Tetra. Sometimes, spinal curvature also occurs as the parasites inflict ever greater damage upon the central nervous system. Death occurs when the parasites invade the brain. A pretty horrific course of events, and no doubt excruciatingly painful for the fish.

If your fish show no obvious outward signs of disease, then I would hesitate to implicate NTD because of the description I've just given. NTD eventually manifests itself visibly in badly affected fishes. If your Congos were affected by this organism, they'd start to look very visibly and manifestly sick in a fairly short period of time, and the symptoms would look confusingly like those of piscine tuberculosis to the untrained eye (indeed, a full histological examination of the dead fish by a specialist would be required to definitively differentiate the two diseases in certain fishes). However, it's worth looking out for other Microsporidians, such as Nosema, that are likely to be more 'stealthy' with respect to outward symptoms. However, Nosema would also strike the other fishes, including the Panda Corys, which you have said are thus far untouched and in good health. Which again adds to the mystery.

One way of sorting this out would be to see if a local college or university biology department would be interested in examining your dead fish. You could do a deal whereby they use your dead fish as teaching material, in exchange for you getting a report on any pathogenic organisms found. This would give you the benefit of a reasonable level of expertise without prohibitive cost. There are also some veterinary scientists that perform analyses of dead fishes for hobbyists - send an E-Mail to the editors of TFH magazine, asking them if they still provide a list of such people (as they did in the 1970s: I have a back issue with a list of names from 1976, though some of those may possibly be dead themselves now!).

If you do end up having a Microsporidian diagnosed, then I have to tell you it's bad news. Microsporidians are insidious, impossible to treat in living fishes, and a bad infestation calls for the 'nuclear option' - strip down the tank, rehouse the remaining healthy fishes somewhere else, and attack the affected aquarium with neat Chlorox bleach. Basically, the only way to wipe out a bad Microsporidian infestation is 'scorched earth' sterilisation, unless there have been some spectacular advances in fish medicine of late.

And with that, I hope that [1] you find out what's causing the mystery deaths, and [2] that it ISN'T a Microsporidian.


Last edited by Calilasseia at 10-Apr-2005 04:50

Panda Catfish fan and keeper/breeder since Christmas 2002

I've lost no fish in the past 3days. But the fish deaths total all the black neons, 6 congos, all the emperors, 3rams and 4 threadfins. No cory, oto, pleco, loach, or gourami deaths. I started running my diatom filter 2 days ago and have done lots and lots of water changes on the tanks. Since I don't know what it is or how bad it is I'm going to wait a few weeks. If there are no more fish deaths I'll try adding a few new congos and restock slowly. If any more fish die I'm going to strip the tanks. Would a uv sterilizer wipe it out? I might be able to borrow one.