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Why do my Fish Keep Dying?

By: Jennie Kermode - Updated: 27 Jan 2017 | comments*Discuss
 
Stress Fish Deaths Dead Fish Tropical

Q.

We have had a tropical fish tank since January and have left it a month before adding fish. We managed to keep them for a while then they died. We have since been and had our water checked and have been told it is ok, we have done the water changes and have since left it for a while.

Two days ago we tried with some more fish and since then 3 have died.

What are we doing wrong?

(Mrs Natalie Swann, 30 September 2008)

A.

This is a bit difficult to answer without knowing more about the circumstances of the deaths, particularly how the fish looked when they died, but there are several possibilities.

The first of these is that you bought fish who were already ill. Sadly, even with good fish shops, this can happen. If so, you may have disease organisms remaining in your aquarium where they could have infected your new fish. This leaves you with two choices - empty the tank completely, throw out any plants, sterilise the gravel and equipment (boiling is the easiest way to do this) and start all over again, or treat the tank (whilst there are no fish in it) with a general purpose antibiotic, hoping to kill off whatever is causing the problem. I recommend Paraguard for this, as it will also help to bind up any toxic heavy metals in the water.

Even though you had your water tested it's possible there is a problem there. It's always better to do your own water testing and to make sure you can understand the results. Read our articles on Aquarium Water Parameters, Water Chemistry and Water Quality for a basic guide. Even if this doesn't help you now it may help to prevent future problems.

It's also possible that your fish died as result of stress caused by the way they were transported. Sometimes this happens as they're moved to the shop and there's nothing you can do about it, but you should take every possible precaution when transferring new fish to your home - see our article on Transporting Fish. Most importantly, you must make sure they have time to adjust before entering the aquarium itself. You can also take steps to minimise stress in the aquarium by making sure there are plenty of hiding places available.

Finally, it's possible that your fish weren't getting suitable food. Sometimes stressed fish won't eat and sometimes fish are confused by being offered a new type of food when they're used to something else. Ask your local fish shop what they feed to fish there and try using the same thing, at least for the first few days. Make sure it all gets eaten up.

When you are ready to try getting new fish, I suggest that you pick a hardy breed such as danios or barbs and get just a few to begin with (enough for a shoal in which they'll feel safe). Don't try to stock your aquarium all in one go, but introduce fish gradually in order to keep things stable.

Good luck!

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[Add a Comment]
one of my silver dollars in my fish tank keeps swimming upside down and then lying on the bottom of the tank for long periods . he will ten move and then go upside down againhow can i get him better . the water in the tank is changed once a week .and i have done a water test which seems ok is there any way i can get him better . all the other fish are ok
ade - 27-Jan-17 @ 5:34 PM
i have just got anew tank 76 liter and over 5 week I have put in33fish and some of the fish got white spot and now they are dying every day I have changed the water every 2 day
cookie - 10-Jan-17 @ 10:29 PM
loz - Your Question:
I got 3 tropical fish and are going white and eyes are nearly popping out what can I do plz

Our Response:
Unfortunately, 'pop-eye' in fish (where a fish’s eye is white or cloudy and bulging), is more often than not caused by long term exposure to poor water conditions, where either the aquarium is overcrowded, unhygenic and/or receives infrequent water changes. This means bacterial infections commonly occur. If the water conditions improve, the swelling of the fish’s eye should abate in time if the fishes are healthy and have a healthy diet. Your pet shop, or vet may be able to recommend possible additional treatment dependent upon the severity of the infection. I hope this helps.
TropicalFishExpert - 29-Nov-16 @ 2:07 PM
I got 3 tropical fish and are going white and eyes are nearly popping out what can I do plz
loz - 29-Nov-16 @ 8:41 AM
I've had my tropical fish for about a year, I've got Molly's, guppies, neons, chinese butterfly s, bamboo shrimp and yamata shrimp, I bought white Molly's two weeks ago and 3 live plants since then ive had nine fish die on me in a week, . I can't understand it, my tank is 4 and a half feet, it took me four hours cleaning it and cleaning everything and yet another fish has died I've also got nerite snails and there was like wee green eggs over my tank please hep
trisha - 16-Jul-15 @ 12:15 AM
@Val - the water should be kept around neutral pH 6.8 to 7.6. with a water temperature at 23-28 degrees C. Given it is a wood eating species it needs several types and while it may eat algae the young eat more. They also need occasional servings of meaty food and vegetables and like to forage for food after the aquarium lights have been turned out.
jay - 24-Nov-14 @ 11:34 AM
Had aquarium running for about three months .Plants look healthy as do the fish though we have lost a few( only one by one and at intervals) but seem to have settled down ok now except we've just lost our second clown Pleco.Both looked fine and were really active up to a day before dying. We seem to have very little algae but alternate days we have put in a Pleco tablet.Any ideas what we're doing wrong.Really appreciate some help Asap thanks
Val - 21-Nov-14 @ 7:24 PM
I have had my fish tank for approx 18 months and not had any problems since i cleaned the tank as normal last week the water has turned murky and green colored any advice much appreciated
buddie - 28-Sep-14 @ 11:56 AM
we have a tropical tank and at the moment we keep losing the fish but dont know why some look ok but some look fat and die and something is popping eyes out of some yesterday we lost 1 guppy and a male and female sordtail
lol - 24-Apr-14 @ 8:27 AM
I set up my fish tank 3 ft by 1 ft by 1 ft on Friday went it brought fish Tuesday guppies and neons and my son brought some shrimp wed but some in the neons and shrimp have died any reason y
fairy - 3-Oct-13 @ 8:38 PM
ive had a tropical tank now for quite a while with all my fish healthy and growing . tiger barbs ,rainbow platties head and tail lights neons and an angel fish , i bought 2 new angelfish and everything was good for a week but over night i lost my tigers , and the next day my platties , my large angels eyes swelled up but he seems ok , i have changed the water and I dont know what to do canyou help please I dont want to lose any more thanks sarah
sarah - 7-Nov-12 @ 5:44 PM
Weve had tropical fish for about 2years now and havent had any problems with our tank. But the other month we bought 2new fish and since then weve had problems. Weve lost 5 fish this week but our fish dont have any sighns of any think wrong with them. Please help we dont want to loose any more of our fish.
booie88 - 2-Sep-12 @ 5:26 PM
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Latest Comments
  • ade
    Re: Why do my Fish Keep Dying?
    one of my silver dollars in my fish tank keeps swimming upside down and then lying on the bottom of the tank for long periods . he…
    27 January 2017
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