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Well can they? Seems to be in my tank that i'll do a water change, the tank will look nice and clean.

However within a few days there is more detritus than ever before on the bottom of the tank and occasionally a dead fish.

I can't test my water just yet (have full test kit at home but it's a bit ruined ) but i will take my water to the lfs on saturday.

Hey bonny,

I'm not sure if fish will be infected by the bacteria that cause dysentery, but we can look at some of the characteristics of the disease.

First, it's caused by a bacterium specie Shigella dysenteriae type 1. It's not hard to get an organism infected, only takes about 10 - 100 bacteria for full effect.

The bacterium Shigella dysenteriae is an anaerobic gram negative rod shaped bacterium. Once ingested, they colonise the intertine and attack the colonic epithelial cells, causing cell death, tissue destruction and eventually death of the infected organism.

Often infection occurs when an organism drinks fecal contaminated water. In the case of fish, highly likely. But how did the bacteria get into your tank in the first place, I can not answer.

Symptoms include bloody diarrhoea, fever, abdomen cramps.
Treatment with antibiotic include ampicillin or nalidixic acid .

Although poor water quality can suppress the immunity of fish, the fundamental cause of dysentery is not water quality. It is the bacteria that lives in the water.

Change your water, treat with anti-biotics.
Even fish that hasn't shown symptoms yet may also be infected, just takes a while for the bacteria to multiply to a number great enough to cause visible symptoms.

Good luck!

I'm not sure if it is dysentery or even a similar disease, i just happened to notice a sharp increase in fecal matter in the tank and fish dying shortly after this.

Now they may be dying due to decreased water quality due to the increase in fecal matter but this is an established tank and i did not think i should be having this problem.

Will definatly get the water tested and see what I can discover from that.

If the faecal matter doesn't look abnormal* then it is probably a correlation to amount being fed... more in = more out.

1/2 the amount you are feeding for about 3-4 weeks and monitor. (don't get alarmed, underfeeding will give your fish healthier longer life than over feeding. All my fish get one food free day per week, and some I have had for 5 years or more)

Also plant matter available for feeding on affects both the waste output and the amt you feed your fish. If there are plants they are eating then naturally you need to decrease the food you give. Also, them eating plants means their waste is different to fish that get only foods that you add (fresh/frozen/dried)

* Abnormal faeces = not in a compact string, white, pale

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~~~ My fish blow kisses at me all day long ~~~

There is actually more than one organism responsible for dysentery in humans, and it is likely that the same could apply to fishes. As well as shigella, the cause of bacterial dysentery, there is Entamoeba, which is a parasitic amoeba that causes amoebic dysentery in humans. I've had this once back in 1981 and believe me, it's not something you want to experience ...

Rhizopods (amoeba type organisms) are food for small fishes. Some of them, however, could be pathogenic. To determine if a pathogenic rhizopod is the cause of your deaths would require trained assistance from a path lab though. You'd need to keep specimens preseved in 10% formalin ready for wax setting and microtome slicing. If you're not au fait with such techniques as triple or quadruple counterstaining with mordanted stains, or the use of phase contrast microscopy, then chances are you'd have trouble identifying an organism in this class.

You could also try collecting the faeces for analysis, but again, you would need trained assistance from a professional pathologist or histologist with several years' specialisation in aquatic micro-organisms. Such people are not easy to find, and tend to charge large fees for their services!


Panda Catfish fan and keeper/breeder since Christmas 2002

Well i've not had any problems for a couple of weeks now.

All ammonia/nitrite readings seem to be fine (although nitrates are a bit high). I'm starting the excess fecal matter was a mixture of stuff that had come out from being buried in the sand and from being expelled from the filter after cleaning it. As i cleaned the pipes on my fluval 304 the other day and the amount of crap i got out of it was pretty shocking

Pipework can get pretty grotty inside in a surprisingly short space of time ... something to go shopping for next time you think on is some test tube cleaners, the sort that are used in high school chemisry labs. Basically they're stiff cylindrical brushes on a wire holder. I've got one for cleaning the undergravel filter tubes and the inside of the powerhead, and it's very effective. Test tube brushes last a long time too, so if you buy a pack of them now, you probably won't need to do so again for, oh, 25 years at least!


Panda Catfish fan and keeper/breeder since Christmas 2002