Ray sudden death syndrome?

[LBathory]

I have had this problem twice. I buy a ray, it is totally healthy, free swimming, active, and pellet trained. After 3 months of being awesome, out of nowhere, it dies. This first happened to me with a humerosa, and more recently with a marble. Both rays were in my tank for around 3 months and were at about 7-8". Both were pellet trained and showed absolutely no signs of distress till about an hour before they died (they were sluggish and the back of their disk began to curl.)
I do a 50% water change once a week and have never lost any other fish due to bad water chemistry.
tank mates were 2 indo dats, a few blood parrots, a tig, and a royal pleco, none of which ever bothered the rays.
anyone have an explanation, or a similar problem? I really want to get another ray, but it's not worth it to have it die after only three months.
Thanks

 

[LBathory]

^

 

[LBathory]

anyone?

 

[Gr8KarmaSF]

http://www.monsterfishkeepers.com/forums/showthread.php?t=224933&highlight=death

 

[LBathory]

thanks gr8

 

[Gr8KarmaSF]

Double coverage for ya!

1. How often do you do water changes?
once a week

2. What percentage do you change?
50%

3. What size is your tank?
48x18x24 (I know it's small, but temporary)

4. What is your stock?
2 indo dats, 1 tig, 4 bp's, 1 royal pleco.

5. What is your filtration?
fx5

6. What do you feed your rays?
massivore and the occasional night crawler

7. How often do you feed your rays?
once a day, twice on weekends

8. How long have you maintained this schedule?
2 months

9. Barebottom or Sand?
fine gravel

10. How long before your ray stopped eating and its death?
an hour, maybe less.

11. Did you add salt for treatment?
no

12. What other meds did you use?
nothing not enough time to diagnose.

13. Did you transfer the sick ray?
no

14. What other info do you think might be helpful?
was perfectly healthy an hour before death.

15. Where was your ray from? Vendor? CB? Wild Caught?
first: WC humerosa 7-8" from shark aquarium. second: CB marble motoro 7-8" from reputable store.

 

[DavidW]

with a tank that size you should be doing at least 25% w/c every other day, if not every day.

 

[LBathory]

for one ray?

 

[sbrodacz]

Did you test the water?

 

[LBathory]

yeah, all params were normal. the ray didn't even have a red belly or anything... im really puzzled. it could have been a short ammonia spike that ended before I took the test or something. thats really all I can assume.