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New Member
May 15, 2018
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Texas, USA

My fish Gill recently passed a couple days ago unexpectedly - and I don't know why. The day before his passing I had a water testing due to an unrelated issue and all my parameters were in perfect condition. My water is also at 75 degrees temperature in Fahrenheit. At the time I had the Angel Fish at topic, another angel fish, a Dalmatian Molly, and a Sunburst Platy in a 20 gallon tank.

Heres the time table:

* 9:00am - I wake up, feed my fish. Everyone is well, nobody looks sick and is swimming and eating well.
* 9:10am - I finish watching them and walk downstairs to carry on my day
* 11:30am - I come upstairs to my room (where the tank is) and see that Gill (the angelfish) is upside down, yet breathing. I panic, and start googling everything I can to figure out what's happening. The entire time he's either leaning against the tank to support him or against an object, as he can't stay up by himself. From the limited knowledge I have about fish and sicknesses, I deduced it was "swim bladder disease".
* 11:40am - I grab my keys, drive to Pet Smart, and ask the fish-lady what to do. She thinks its also swim bladder disease. She tells me to purchase a "breeding net" to isolate the fish inside the tank, and so get some "general cure" fish medicine, and that the medicine will kill all parasites if any.
* 12:00pm-ish - I get home, run upstairs as quickly as I can, and see that Gill is doing even worse. Panicking, I peace together the net and place him in it. He's barely sitting up, relying heavily on the net for support. I dump the appropriate amount of medicine into the tank and wait, sitting there hoping he gets better.
* 12:15pm - he looks dead, but isn't. He's barely able to sit up, but he's breathing. I walk downstairs to get some water and tell my family about the situation.
* 12:30pm - I walk back into my room where the tank is, and Gill is laying flat on the bottom of the net - not breathing at all.

I do not know what killed him, have it be a parasite or birth defect - but I want as much knowledge as I can get so it doesn't happen to my other Angel fish.


Fish Guru
Jan 26, 2008
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Perth, WA
I don't suppose you took any pictures or a short video of the fish before he died?

Did the angelfish look bloated or really fat when this happened?
Was the angelfish breathing heavily?

What was the unrelated issue the day before the fish died?

What did you feed the fish before it died?

What medication did you add to the aquarium and how much water did you treat for?
If you treated for 20 gallons you might have overdosed but the fish was going to die anyway so if you did overdose you probably put it out of its misery.

To work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.

There is 3.785 litres in a US gallon and 4.5 litres in a British gallon. You can use the calculator under the How To Tips tab on this forum.

When you measure the height, measure from the top of the gravel to the top of the water level.

Without seeing the fish I can offer ideas about what killed the fish but can't be 100%.
If the fish became really fat when this happened then one of its internal organs probably ruptured and this caused the fish to have problems swimming and subsequently caused its death. The most common cause of organ failure is bacteria or protozoan infections damaging the organs. When the bacteria or protozoans do sufficient damage to the organ, it ruptures and the fish dies from organ failure and internal bleeding.

If the fish did not suddenly bloat up, then it might have still had organ failure, but the organ did not cause the abdomen to fill with fluid.

If the fish's swim bladder popped, that would cause the symptoms you described but it doesn't always kill the fish.

If you get any more fish acting strangely, post a photograph on here and maybe get a short video of them acting unusual and we will have more to go on.

Depending on what medication you added to the tank, it might have wiped out the beneficial filter bacteria. Monitor ammonia and nitrite levels over the next few weeks and reduce the feeding to once every second day until you know the filters are functioning properly.

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