My fish keep dieing

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Fish Fanatic
May 5, 2004
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Kent, England
My tank has been up and running now for 3 months. It is a 27ukg tank. All the levels seem to be ok, ammo 0, nitrite 0, nitrate 10ppm before weekly water change, phosphate <1mg/l PH and PH of 8.0 (normal for area and the same as the LFS).

I bought some cardinals (not from my normal LFS) and 1 died the next day (no sign of diseas) and I just put this down to stress. About a week later 2 of my glass blood fin tetra dies but they looked like they had bent spines which I hadn't really noticed before (again no sign of diseas).

Then I bought a male neon blue and red dwarf gourami who died 2 days later with what looked like a swollen area under his mouth. So I took him back to the LFS and they exchange him for another. The next day I noticed that he had pop eye which he got over night! So he went back to the shop and they exchange him for another. He seem to be ok after a week except for a small sore next to his mouth which I put down to his continuous rubbing up and down the glass looking at him self.

I then bought a Golden Ancistrus (from LFS). He was OK for a couple of week.

Then I bought 2 female and 1 male guppy (not from my normal LFS) and two days later 1 male and 1 female died. I replaced these, then 1 day later my golden Ancistrus died. I have now replaced the plec with an L015 which I am now worried about because the male gourami has died, and then today a cardinal died (dis coloured so may be old age).

Have I just been unlucky or is there something seriously wrong. One thing that I have thought of is that the back of the tank has not got a cover so could the fish be getting stressed as the tank is in the middle of the room.

Any help would be great.

I can't imagine that stress like that would kill your fish....perhaps there is something else in your water you can't test heavy metals or something...either that or the fish you are buying are coming diseased....

I can't think of anything else...everything else seems OK...

Remember though, cardinals do prefer a mature tank...that doesn't account for the guppies and catfish though

Good luck
Thanks for the quick reply Chooklet.

I could only think that it must be diseased fish as my other tank has been fine, and I do everything the same and use the same water treatments etc.

I did put a clay (red type) flower pot (which I soaked for ages before putting it in the tank) in the tank and kept an eye on the PH witch didn't shift.

I have an aerator in the tank and an external filter (which is in the hood) with lots of plants and bog wood.

I have been increasing the stock slowly and the water parameters have been stable for ages (after about 2 weeks of setting it up). The clown loaches (which I was told are very fragile fish) have been fine with know problems (touch wood!) and the black phantom tetras whitch I used to start the tank off are also still going strong.


Hi there.. sorry to hear about your fishy problem :no: .
I think one of the main reasons for your problems is the high PH of your water.
I have the same problem myself, mines about 8.2 (some of that is due to new gravel wich can make a 0.6 change to water until its had enough water over it)
Tetras of any type prefer slightly acid water. around 6.5PH so thats why you are having trouble with them. Guppies again .. prefer around 7.0PH and are very difficult to keep alive I have lost 5 females already due to fin rot/dropsy all caused by stress due to the high PH range.
The gouramis tend to be a little hardier but I have lost one also with the same symptoms as yours. Swollen mouth and no other signs of illness, comes on within 24 hours dead in 48. It seems a big problem if you read through the other forums.

It would be interesting to know what has surrvived in your tank. And does it have plenty of cover for the fish as they need their privacy too. Plus its not a good idea to have the light on for a while either.

I would recomend a hospital tank to isolate them for a few weeks until you know there are no signs off illness. That way you won't be putting you fish in your main tank so much at risk. A tank of about 5 gallons is ideal that way there is enough space for a few fish and its not top expensive to treat. Don't use gravel on the bottom though, just keep it clear that way its easy to keep clean in between uses. Add a few plants either with weights or in the small pots you can buy for cover to reduce stress (always clean in between to avoid disease spread) Get some melafix from the LFS and maybe try adding it just before your fish arrive and some stress coat too. Do daily water changes, as without the gravel your tank won't be cycled hense the adding of the stress coat.

Give it a go, it will be cheaper in the long run than the cost of replacing lots of fish. Also find out what fish best suits your high PH too. ;)
Thanks for the info littleme1969.
My local LFS has the same wter parameters as me and said that the fish will be ok with a PH of 8.0 so fish from there should be ok. I don't want to start with trying to reduce the PH level as this probably make things worse.

The cardinals and guppies that died were from another shop aout 20 miles from me so I suppose there is a chance that the water conditions are different enough to cause problems.

There are alot of hiding places in the tank (its a planted tank with quite a few plants) + bogwood and plant pot.

I have just bought a backing for the tank as this may help a little.

The fish that have survived so far are 3 clown loaches, 6 black phantom tetra, 2 femal and 1 male guppy, 1 female gourami, 4 glass blood fin tetra and 4 cardinals.

So fingers crossed that no more die but I won't be replacing any of the fish that die until I am sure that there are no more problems.

I might think about a hospital tank but I am running out of space as I have a fry tank as well, but I could put a spare samll under water power filter and transfer that to the hospital tank if and when required so no cycling will be required.

Thanks for the help


PS nice tank littleme1969. I have the twin hex as my fry tank.
Just phoned the fish shop where the cardinals and guppies came from, and the PH level is 8.2 in their tanks.

Chasing Puck, I leave the fish in the bag for about 20mins floating in the top of the tank with the lighs off. I then net the fish into the tank and leave the lights off for another half hour.

Cute pig by the he yours?

They say you should let a little water into the bag and then leave for another 20 mins or so before you let them into the tank...

I think a big problem in the UK is most of our fish from LFS are imports. The poor little beggers have been through so many changes by the time they reach us they are already stressed to a high degree. Plus speaking to my LFS they tend not quarantine anything for more than a few days if they are happy with the supplier. Meaning.. you go in and buy the fish and they have had possibly 3 moves within one week. :/ :no: .. No good news for any fish :-( . I bought my first batch from Pets at Home and never lost a fish out of 11 :) even though my tank was a new setup. They were added over the period of a month though. I did have a chat with the guy in there one day and it turns out all their fish have a mimimum quarantine period of 2 weeks :) . So all the sickly fish due to transit never make it to the *for Sale* tanks. And they never stock Livebearers ... the reason given was what I have found myself.. they are very sensative and hate such things as PH change. Too many died so they stopped stocking them.
Which is the reason I went to a specialist shop. But so far out of 6 fish only one male has survived despite my best attempts to medicate etc.

Knowing what to do for the best is the hardest thing :S

I hope things settle down for you.. nothing worse than watching things suffer :-(
The pig is mine, his name is Goldy. He is just one of the 14 pigs that I have.

I agree with the comments about transporting fish etc. My local LFS which I thought was good, only keep the fish in quarantine until they start eating!! No real time which I thought was strange.

I was in Pets at Home at lunchtime and the one here does stock live bearers like mollies and platies so it must be down to the managers discretion.

Try this next time: Put the fish and water in a jar. Add one cup of tank water every 15 minutes until you've doubed the volume of the water from the bag. Pour out half the water, repeat. Net the fish carefully and release in your tank.

This provides a gradual introduction to your water, as well as diluting any built up ammonia. Floating the fish isn't really a good plan, especially if you have the lights on--since the bag is so close to the lights, it starts heating up, and the fish isn't exposed to your water until it's put in.
Thanks for the info Chasing Puck. I will give that a go next time. I never float the bag with the lights on though.


The first thing I would do is not add any more fish. The worst thing you can do when you have a problem is add more fish. I found that out the hard way ;)

Sounds like a bacterial infection to me, brought in by some of the new fish. Cardinals haven't been very good for a while. They all seem to be wild caught.

Your best bet is to carry out a 50% water change to dilute any polutants and to take down any parasites and bacteria. I'd then treat with Melafix or another good bacterial remedy. Don't bother with Interpet or King British, they're crap.
Pop eye is a sign of bacterial infection, as are wounds and ulcers.

The ph won't make any difference at all. It was probably too high for the Cardinals especially if they were wild caught but other tank bred fish, including most Tetras should be fine. My ph is above 8.0.

Wait a while until you get some more fish. About a month should do it. Dont get more if fish keep dying though. ;)
I have to disagree with the PH won't matter bit!.. most tank bred fish don.t cope well with above a 0.3PH change in water.. its well documented on both here and in many books and internet stuff I have read. Hardier fish cope OK but the more delicate fish like livebearers will always fall pray to it. Change in any water conditions will stress the fish another well known fact. So I feel the only way to get round it is minimal change. Trying to keep the peraminters of your water as near to where you get them from as possible. Then slowly introduce your own tank water to the fish while in isoltaion that way if you have any probs its easier to treat them and won't upset whats going down in your main tank B)

But no doubt some one won't but hey :rolleyes: that's what were here learn from each other and each others mistakes :thumbs:

I still think that tropical fish in the UK will always be an issue due to the stress they encure in transit/import... so we seem to always be on catch up over here :-(
I think most problems attributed to so called pH-shock is actualy related to the change in TDS--which usually changes along with the pH. Since pH is easily tested, and TDS requires a bit more work, pH is an easier reference, similar to how non-toxic nitrates are used to monitor other, toxic substances that we can't test for (not valid for planted tanks!).

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