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Unknown freshwater issue


brett2003

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Hello all,

I'm having an ongoing (and thus far inexplicable) problem with one of my freshwater tanks - there's no 'outbreak' per se (in the sense that only one fish is ever ill at a time), but I'm losing approximately one animal per fortnight, all with the same symptoms - lethargy, difficulty staying afloat (sinking to the bottom, floating on odd angles).

Generally, there are few to no outward symptoms, although the Rasboras that died did have some discolouration - posted about here: http://www.fnzas.org.nz/fishroom/viewtopic.php?f=25&t=60847. This has so far affected at least some Peppered Corys, Harlequin Rasboras and a Dwarf Gourami - so far, my Emerald Eye Rasboras are totally unaffected, as are my Clown and Dwarf loaches, and all four of my loricariidae (two Otos, one fantail Bristlenose, one 'regular' bristlenose).

Water chemistry is fine, so far as I can see - no ammonia, no nitrite, pH is around neutral and doesn't fluctuate by more than about 0.1 - 0.2 over a 24 hour period, temperature is steady around 25 - 27°C, nitrates are generally around 10ppm at the outside.

We have two other aquariums that are being filled from the same water supply, and neither of them are experiencing similar problems. All the tanks get the same food as well, so I don't think it's that.

The only water additives used are small doses of Nutrafin kH Booster (5-10mL with each 48L water change) and Flourish Excel (4-5mL per day).

Does anyone have any idea what could be causing this? It's getting a little expensive (and of course it's not cool to watch your tank population halve over a three month period).

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The tank is 150L

The flow is reasonably good - it's a 1200 L/hr canister, but it's actually a little overpowered, so I've got the spray bar turned towards the back of the tank (if it's facing forward, it creates a pretty serious current) - there's not really ever any visible detritus *but* there are large numbers of small snails that seem to deal with anything that arises pretty quickly.

I should have also said it's been through a Melafix treatment recently (some of the Neons had fin rot - not sure if it's related or not, since none of the other affected species showed any signs of skin, scale or fin damage)

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Gah, I really hope not :( Would that be associated with swim bladder issues? All of the affected fish so far have had that.

The one thing I haven't tried yet is a broad spectrum antibiotic, so I suppose I should do that first before I do anything *really* drastic like (as that article suggests) stripping down and disinfecting :-/

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The signs of Piscene Tuberculosis can include:

Wasting disease. typically pinch bellied and from the front or rear the "back steaks" are concave rather than convex.

Bent spine or bone deformities.

Ulcers or open wounds.

It can attack the liver and cause swelling like dropsy.

It can attack the ovaries and stop egg production.

It breaks down the imune system so can make the fish more prone to other diseases.

It can therefore be difficult to diagnose because most of these signs can also be something else.

It is caused by a bacteria and is zoonotic---that is can be transmitted to humans (generally through cuts or broken skin on the hands). This is the main reason for the requirment to wear long waterproof gloves when quarantining fish.

If they do not improve after deworming that would be my next choice.They are gram positive micobacteria and they are slow growing and have a protective slime coat, both of which make for difficulty in treating with antibiotics. When I imported goldfish one type came up with PTB and Maf (in those days) took them away to be destroyed, they did not suggest a treatment. The fact that they took away the wrong fish is another issue for another day.

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zombiefish and i have been having the same problem. symptoms all similar, seemingly healthy fish, random deaths, weeks sometimes months apart. affected the africans the worst, wiped out her whole tank :( and i suspect it might have also hit an oscar, texas and bgk from my tank as all these fish have died similar and unexplainable deaths. there was one group of hybrid african cichlids we shared between our tanks a while back and they are the only fish we have ever shared between our two aquariums. all of them died from this "fish plague" while they were still juvis..

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Have you looked at the dead fish with a magnifying glass? Whatever it is might be invisible to the naked eye. You could do an autopsy and see if its some sort of internal parasite although certainly sounds more like swim bladder. Do o have the same types of fish in your other tanks?

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Often by the time I find them, they're already covered in a film of whatever it is fish get coated with when they die :( The smaller ones often just vanish - I never find them at all. I'll try if/when it happens again to inspect more closely.

In terms of species - pretty similar - Rasboras, Tetras, Gouramis, Loricariidae and Loaches - not precisely the same species, though.

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tanks don't share water supply or equipment - so its not poisining for us.

fish would be fine, then id notice one with activity level dropping off, then within a matter of hours it would be dead. Im talking like 1-3 hours. some of them looked like their scales had all fallen off - others looked perfect, just dead. some just turned up dead with no pre warnings.

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i wonder as a lot of us are north shore/auckland if we have purchased fish from the same shop/person and there is something slow acting taking them all out?

Hmm. Most of my stock are from Hollywood Albany, with smaller numbers from Hollywood Mt. Roskill and one or two from PetStop Dominion Road.

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just as a bit of a stab in the dark does your tank have good aeration? you know Flourish Excel decreases the oxygen content in the water just a idea tho...

just thought it might be a reason as it takes a while for signs to show and then death

tho i had the same problem in a community tank was losing 1-2 fish a week got most of the fish from Hollywood fish farm Albany and animates wairau park i am a fan of both those places because the staff are great but its got me thinking..

(don't have the problem anymore because i sold the tank and most of the fish in it)

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