Freshwater stingray

[mikeklh]

My motoro died today. He had been acting strange since Sunday and I was wondering if anyone out there can help me identify what went wrong.

Symptoms:

1) Swimming the length and breadth of the aquarium at great speed mid - water and crashing into the glass

2) Spasming occasionally, like he was having some sort of seizure. I think he ate some of the live shrimp I'm feeding to a new stingray, a female I bought 2 weeks ago, and the spasms started more or less immediately after that.

3) Lying quietly in one corner on the substrate. Usually, he's either very active or buried in the substrate.

4) Refusing to feed. I hand - feed, and he's always coming to the front whenever I'm near.

I asked at the shop and they thought it was just him showing off to the female. She, and the rest of tank's inhabitants, does not seem to be affected.

I'd love to get another but I'd like to know what went wrong first.

 

[Paul_MTS]

very strange sounds something like when 1 of mine died. I did a water change and soon after that he went nuts like that but mine died within a few hours like that, whilst the other 1 in there was fine!

what size is the tank?

 

[mikeklh]

Tank's 54" x 18" x 18". I know it's a bit small for stingrays but an upgrade to a 7' x 3' x 2' ( the biggest that will fit through the door!) was on the cards.

Current fish include a 12" blue arowana, a 6" motoro, and 2 6" plecs. My male motoro was about 9".

I check the water quality every week and found nothing unusual.

I normally do a 25% water change every week and did one on Saturday night after he refused to eat.

 

[Paul_MTS]

Any signs of anything on him? marks, scrapes, redness?

Just to note if those depending on plec species keep a close eye on them as some plecs will quite happily suck on the rays.

If the water was fine then I'm clueless after that really. Looks like it's another mystery death for the ray statistics.

Any chance of some pictures of your fish and tank? Nice to see another aro keeper on here!

 

[mikeklh]

No injuries, as far as I can tell.

Don't think any of the plecs were at fault as I've had them all in the same tank for about 10 months now.

I wonder if anybody does a post - mortem. It'll probably cost an arm and a leg, but...

I've got some pics, but don't know how to upload them. I'll send you an e-mail if you'll give me the address.

 

[CFC]

I'm wondering if the mysterious death could have anything to do with the live shrimp?
As we all know rays and other Elasmobranchs are sensative to heavy metals and in particular copper. Shrimps being scavengers quickly pick up any toxins from their enviroment, i remember a few years ago a news artical saying how sea food collected from polluted coastlines had been found to contain dangerous levels of mercury and other poisonous metals.
Could it be that the shrimp had been collected from a polluted source and that the ray being a enthusiastic feeder and larger than the new female ate enough of the poisoned shrimp for it to affect his nervous system?

I feel that the water supply can be ruled out as there are several sensative fish in the tank but only one has been affected.

To be on the safe side i would avoid feeding any more of the live shrimp and stick to frozen alternatives, motoros can be stubborn toward dead foods at first but i have found that if you offer a mixture of foods along with some chopped earthworms or frozen bloodworm and then slowly reduce the ammount of earthworm/bloodworm at each feed they soon start to realise that if they dont eat the other stuff they will be hungry.

 

[mikeklh]

I did think that the live shrimp had something to do with it, but ruled it out as I'm sure both the arowana and female motoro ate more than he did. Was keeping an eye on the tank to make sure she got her fair share!

His spasms started more or less after just a couple of shrimps. Thought he was choking at first, but he seemed fine after.

I'll ask the LFS where they got the shrimps from tomorrow (closed today). I'm pretty sure the proprietor catches his own shrimp. That should make it easier to know whether his source is polluted, shouldn't it? Will keep you updated, CFC.

Thanks for the feedback, Paul_MTS & CFC.