Angelfish Died Suddenly - WHY???

[kalihat]

Hi, it's been a while! I have a 75gal freshwater tank, that's home to 4 marble angels, and 8 corries. Last weekend the Black Moor I had got sick, it seems it was dropsy. He didn't make it unfortunately. Now today, one of my angels was just was lying on the bottom of the tank, dead. I hadn't noticed any odd behavior that would indicate any illness. I took him out and then tested the water, and I got:
0 ppm Ammonia
0 ppm Nitrites
40 ppm Nitrates

I've got an Eheim filter, it's meant for a 125gal, and the tank was cycled before any fish were put in, but that was about a year and a half ago. I got these angels very small, so they're about 4 years old. I would imagine the life span to be longer, but with no visible signs of illness, was it just old? I want to try to figure out if it's something I can't see so that I can treat the tank to save the other fish. I fed them after removing the one that died, and they all ate like normal. Any ideas what could have caused this death?

 

[kjr928]

Well, I don't think it was age, seeing as angels can live 10 years.

It's also hard to say what could have been wrong with your fish, as your water parameters seem pretty normal & you hadn't noticed any unusual behavior.

For now I would do a large water change and pay close attention to your remaining fish. If any of them start showing signs of illness I would remove them from the tank to prevent any further spread.

Also, a black moor is a cold water fish and doesn't belong living with warm water, tropical fish. So I don't recommend getting another one.

 

[kalihat]

Thanks, I'll do a water change and keep my fingers crossed!

As for the Moor, you're right, I just had nowhere else for him to go, but I already said no more goldfish after him!

Thanks again!

 

[NUMB3RS]

Angelfish are fragile, do you see any other signs of illness on the other Angels?

 

[Lupin]

Angelfish are fragile, do you see any other signs of illness on the other Angels?

Not all angelfish are that fragile enough to drop dead without showing symptoms that would have weakened them and slowly kill them. Marble strains are not really that delicate. The OP has stated she has not observed anything wrong.

Kalihat, could you please test again and see if the water parameters are still within safe range? What test kit do you use? Do you know the date when it was manufactured? What do you feed it? Did you match the temperature when you did a water change?