I've been keeping fish for about 20 years, both cold and tropical, but I've never had this happen before!

I bought 5 fish 2 days ago to go in a new aquarium set up for my children. Since we bought them they have been happily swimming in the tank fins up, fine. Over the space of an hour tonight 2 fantails went upside down, I know swimbladder issues go with them, so wasn't too worried, next thing they are floating, within 20 mins or so the 2 goldfish went on their sides.

I got the goldfish into a bucket of dechlorinated water, but I think they are dead too.

All that is left is a very pregnant danio.

She is floating in a bag in a bucket of fresh dechlorinated water. Do I put her in? atm she seems absolutley fine. What is the best thing to do????

Please help!

Hi soz no advice! didn't wont to be rude n read n run! welcome! i'm sure you will get some advice soon.

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Mr Benjamin: Shih Tzu
Oscar: Shih Tzu
Casper: Snobby puss
Urwin: Tortoise
RIP Candy: Long haired Colly
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RIP Saxson: GSD
RIP Blaze: GSD
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Hello, thankyou for replying! I'm feeling rather lonely with this little fish, I have put her into the water in the bucket, only a small amount of the tank water went i with her as I really feel there is something wrong with it. Could it be to do with the weather? The 1st pet shop I went to to buy the fish had closed the fish section because they said the weather had caused a problem with their water quality and they had lost some fish???

At the moment Sascha the danio is still swimming and looks ok, but Idaren't go to bed now

Oh dear! such a worry for you! i would not like to advice you, as i have forgotten more than i remember! my Dad used to have a 6 length by 2 wide by 3 in depth Tropical fish tank! the fish in there where HUGE! sorry am not helping am i, hope it all goes ok for you!

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Mr Benjamin: Shih Tzu
Oscar: Shih Tzu
Casper: Snobby puss
Urwin: Tortoise
RIP Candy: Long haired Colly
RIP Shane: GSD
RIP Saxson: GSD
RIP Blaze: GSD
RIP Buddy: cockatiel
RIP Lucky n Fluff: Hammys
RIP Cheeky n JoJo: Budgies
RIP Diggit: Nether-land Bunny

Hi there, sorry to hear about your fish

I think a bit of background information would be useful at this point, so if you could answer a couple of questions?

Firstly, how did you cycle the tank and for how long before you got the fish?
If I'm reading correctly, you had four goldfish and one danio? Two fantails, and what were the other two goldfish? Just regular common goldies?
And these were all bought and added to the tank on the same day, is that correct?
What size tank is it?
And lastly, did you test the water? If so, could you post the results please?

I'm not much of a fishy expert myself, but hopefully someone else will be along soon to help us figure out what went wrong

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In a lot ot cases, there's little point in removing the fish from the main aquarium (effectively quarantine) with swimbladder problems; unless the cause is contagious. Lowering the water level to around 10cm/4" often helps, as pressure increases with depth. A lower water level places less pressure on the fish and sensitive organs such as the swimbladder. The swimbladder itself is a gas-filled sac that is directly affected by pressure.

Ignore what the aquatic store has said about weather affecting the water quality. This is absolutely crap as there is no possible way the weather can affect the water quality inside an aquarium - an aquarium is essentially a 'closed-off' environment. The only thing the weather can do is cause the water temperature to fluctuate, however that is perfectly natural.

Personally, I would suspect a severe bacterial infection given that all of the fish are affected. Infections in fish are normally caused by stress, which in turn of often caused by poor water quality. Aquatic diseases are found in all aquariums in tiny background populations and pose no risk to healthy fish. However, stressed fish have compromized immune systems and are prone to infection.

It could be that the fish were already infected when you purchased them from the store, however that would be difficult to prove unless you can visit the store again and look for any infected fish. It would be a very good idea to test the aquarium water for pH, ammonia, nitrite and nitrate.