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Sudden fish deaths no apparent cause, please help before there's any more casualties

9K views 6 replies 2 participants last post by  Beetroot 
#1 ·
I had a couple of sudden fish deaths last week which I thought were a one-off, but now there's been another...

15 gallon freshwater tank with live plants, been set up over 2 years

Ammonia 0, Nitrites 0, pH 7.2, temp 26 degrees centigrade, fluval U2 filter

Tank has a 10-15% weekly water change with the filter medium cleaned in old tank water. Substrate is largeish smooth pebbles, a sweep round with the net once a week gets rid of any rubbish on the bottom.

Currently 3 young fairly small weather loaches, 1 panda garra, 1 otocinclus, 1 black widow tetra, 1 white skirt tetra

In the past week I have lost 1 gold ram, 1 aged guppy and 1 otocinclus. I noticed that the ram and the guppy were missing last Tuesday, and found them at the bottom of the tank with no visible symptoms. They'd been acting perfectly normally up until the day before, so I could only come to the conclusion that something toxic had got into the tank or the live food they had eaten on the sunday evening had something bad in it. (I tested the water that tuesday, and the parameters were as above, which are the usual readings for my tank).

All the other fish were perfectly fine, so I added a couple of teaspoons of salt and put an aerator in the tank.

However, I arrived back from a weekend away today to find an otocinclus dead as well. He too had been as active as usual before I left- from the look of him when I found him I'd guess that he died on Friday or the Saturday. I had done a normal water change and filter clean on Thursday (I use water straight from the tap with dechlorinator)

I honestly don't know what to do as there are no symptoms to treat. The only thing I noticed was that even the fish who had definitely not been dead that long were smelly when I fetched them out, which I have not noticed with previous fish deaths. The water itself doesn't smell.

Any ideas?? I am planning to take some water to the LFS tomorrow morning and maybe buy some new dried food just in case, as we've had the stuff we've got quite a while. However as the otocinclus only eats algae I am not sure that it could be their food.

Is it possible that it could have been something in the live food (daphnia) that they were fed a week ago?

Please help, I am very attached to my fish! :-(

BTW the guppy had been in the tank for just over 2 years, the otocinclus for just under 2 years, and the ram for maybe 3 months
 
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#3 ·
Do NOT add salt to an aquarium with loaches and otos, salt is dangerous to scaleless fish. Otos are extremely sensitive to water parameters, and can only handle a small range. Also if you plan on keeping otos please keep them in groups of three or more. Can you tell me what kit you are using to test your tank, just so I know how accurate it is? Didn't mean to sound snotty by the way XD
 
#4 · (Edited)
Really? I knew about them being sensitive to medication but have been adding small amounts of salt to the tank for years with :s will avoid in future then. I doubt the salt was anything to do with these deaths though, as I hadn't added any for quite a while before anyone died, and I did not put any salt in when I did a water change on thursday so had reduced the salt amount before the oto died. The water tests are API ones.

Was actually planning to get another oto for the two that we had before this disaster :( if the other one doesn't die will definitely get a couple of friends for him. He is currently swimming about and munching on leaves and rocks in his usual manner.

Nothing different has happened recently that would have affected the water parameters as far as I know, but will definitely post the tests the fish shop does tomorrow in case mine aren't accurate

I'm just finding it so odd that they are literally fine one day, and dead the next, especially as the other fish are completely fine.

Thanks!
 
#5 ·
Hmmmm, if there are no symptoms the only thing I can think is there is something going wonky with your parameters. I would definitely get it tested by the pet store and get the readings. Hopefully someone else will have more ideas. I'm sure they will.
 
#6 · (Edited)
I did wonder if it was some kind of bacteria as they were more smelly than usual when they died, though the water wasn't smelly, but I'm not anxious to tip any anti-internal bacteria stuff into the tank...

Thanks for your help!

Oh btw just checked that the test kits are in date, they are and come back with definite zeros, hopefully the pet shop will have some advice... I just hope there's nothing else strange in the tap water!
 
#7 · (Edited)
Just an update here...fish shop has pronounced the water to be perfect, so I suppose that at least rules one thing out and shows that my test kits are accurate, but still no idea of what's wrong! All the remaining fish are still alive and normal today.

The only thing the guy at the shop could think of was firstly if one fish has been killing the others, but I haven't had any bullying problems and the fist two fish to die definitely died unmarked. Secondly, some internal infection, but surely some symptoms would have shown up beforehand?

Might sound silly but I assume that if they had been electrocuted the whole tank would have died?!

So do you think it's worth putting a reduced dose of Interpet anti-internal bacteria in the tank or just wait and see what happens...? Or any other suggestions?

It just occurred to me that there's some emergency sewer repairs going on near to where I am...do they usually put extra cleaning chemicals in the water supply in the UK when this happens? As the fish deaths both happened a day or two after water changes.

Thanks
 
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