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Author:

Boris01 [ Dec 6th, '09, 18:20 ]

Post subject:

mystery silver perch deaths ....

Ok why are my silvers dying ?

Ive got 20 silvers in my trout system , theyre in a seperate tank ( trout in 3 , silvers in one ) and cannot get through

water tests are fine , a small amount of ammonia
plenty of aeration , temps are at about 20 - 22

I found 1 dead silver , looks like it'd been dead for a day or so , and one that was JUST dying as I found it - floating upside down , not breathing

the old dead one had blood showing on its skin and looked as if it'd been sucked up against the pump ( almost lesion like , but didnt really look that bad )
I moved em all into the next tank across after taking all the trout out of it to try and cancel out the pump-sucking theory, then checked the insides of the barely dead one - no food in its stomach or guts or anywhere

another started to float upside down after I moved them , all 3 dead ones are the biggest ( only 20cms though , Im still unimpressed with this batch of silvers )

Theres no metal or anything leeching into the system , the trout in all the adjoining tanks show no signs of anything

nothing much has changed in the last 2 weeks since I put the silvers in , except for a slight Nitrite spike last week and a slow 20% or so water change

pH is ( VERY ) slowly climbing up from below 6 , its now at 6.6
the only thing Ive added is :

-under half a bag of dolomite , which is dissolving so slowly that it looks the same as when I put it in
-1 500g container of Eco-Rose at 1 tablespoon a day till I ran out

The silvers are eating the same food as the silvers in the other system ( which show no signs of anything )

Ive ruled out the temperature
Its not a water quality issue to do with Nitrite / ammonia

It could be :
-not enough salt - do silvers NEED salt ?
-silvers being harmed by 500g of ecorose in 3500L of water ( I assume not , or people wouldnt recommend it )
-one small dead caterpillar I found in the same tank ( I dont spray or use pesticides )
-nothing in its stomach - maybe the big ones decided to stop eating ?
- a disease thats come from who knows where , that affects my bigger silver perch and doenst bother trout
-them dying from being embarresed about their pathetic growth rate

I know "add salt"

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Author:	jessy [ Dec 6th, '09, 18:26 ]
Post subject:	Re: mystery silver perch deaths ....
OBO and ROZ are tthe people for this job .....no fun Boris..all the best ..and I am no help sorry

Author:	Boris01 [ Dec 6th, '09, 18:27 ]
Post subject:	Re: mystery silver perch deaths ....
eh Im not too worried if they all die , as long as it doesnt affect the trout , but I want to figure out what it is

Author:	RupertofOZ [ Dec 6th, '09, 18:53 ]
Post subject:	Re: mystery silver perch deaths ....
In the photos... there appears to be something protruding from all three fishes gills... Did you happen to check the gill colouration at all??? As for the EcoRose.... I'm astounded that you've used the entire 500g.... Whenever I've used it... I've used about a teaspoon-tablespoon.... to move pH about 0.4.... The whole 500g sounds extraordinarily way too much.... unless your pH was way, way higher than 6.0.... i.e around 5.?... something.... in which case moving it back to 6.6 might explain the deaths... pH change... Combined with the dolomite... it sounds as though this might have been the case... P.S.... as a general rule...... DONT add more than one thing to your tank at any one time... It makes it difficult/impossible to determine any detremental results.... and/or it may well compound any detremental effect.... Why were you adding "dolomite" in the first place.... and why did you add the EcoRose at the same time???

Author:	Boris01 [ Dec 6th, '09, 19:16 ]
Post subject:	Re: mystery silver perch deaths ....
bad photos - theres nothing on the gill thats its fin the gill colour was fine , looked like 2 were healthy fish to me , the oldest dead one just looked like it'd been dead a day or two I added about a kg of dolomite , supposedly to dissolve as slowly as the lump of limestone thats been in there for a year the EcoRose was added a tablespoon every day or two into this 3500L+ system , to try and raise the pH ( as I said in my other thread , from below 6 - I cant tell what it was exactly cause thetest kit only goes down to 6 , I assume it WAS 5 or so ), IOve been doing 3 pH tests a day for 2 weeks and its only moving really slowly its at 6.6 now and it took a whole container to do it , over a period of about 2 weeks ( no my pH test isnt off - I added some to a few different buckets of water to see if it was reading right / changing the pH as much as I thought it would ) I added the Ecorose at the same time as the dolomite ( well , days apart ) as the dolomite wasnt dissolving and I wanted to shift my pH a bit quicker that a month or two that its going to take the dolomite to do Ive added 3.5kg salt , and will see how that goes overnight , if theres more deaths I'll add another 3.5kg Im not going to mess around seperating these 18 remaining silvers ( not that Ive got another tank ) and super-salting them & Im not putting them back in with the other 60+ silvers in the other system incase it IS a disease - I really dont care if they die aslong as it doesnt affect the trout , I'll just have to find some fish to tide the system over for 3 months till the new trout arrive

Author:	RupertofOZ [ Dec 6th, '09, 20:07 ]
Post subject:	Re: mystery silver perch deaths ....
Ok Boris... if the pH was around 5.0-5.5 ... then the Silver deaths are probably due to pH exposure... and not related to the adjustment... other than perhaps they were already weakened... I've found Silvers to be quite sensitive to pH at that end of the scale... For general reference... Dolomite is... Calcium Magnesium Carbonate... and like shellgrit (Calcium Carbonate)... is a slow (er) pH buffer... than a BiCarbonate buffer... If people need to move pH a bit quicker... as perhaps in this case... "slaked" or "hydrated" lime... Calcium Hydroxide.... is probably a better option... as it's far stronger... Use sparingly, over several days... (which you did quite appropriately Boris)... to adjust pH...

Author:	Outbackozzie [ Dec 6th, '09, 20:14 ]
Post subject:	Re: mystery silver perch deaths ....
Yeah, I'd go for pH as the cause....what % protein food are you feeding them?

Author:	Boris01 [ Dec 6th, '09, 20:16 ]
Post subject:	Re: mystery silver perch deaths ....
another strange thing : the silvers are in a tank at the far right of the system , pump in there feeds two growbeds above , returns to same tank and adjacent one . theose two tanks are joined with 50mm pipe , the 2nd one joins to the left of the system through another 50mm pipe ( its 4 buried tanks & two above ground tanks , joined together in a line with 50mm pipe ) everything I added , was added slowly over the course of a couple weeks to the FAR RIGHT 2 tanks . to get to the silver perch tank at the far left , whatever I pput in had to dissolve through atleast 3 consecutive tanks to get to the silvers .... So Rupe I could possibly say its : cold water ( 18 - 20 ) getting slowly warmer ( 22 today ) increases the perchs metabolism and thus they get affected by less than ideal water parameters , nitrite spiked to 1 last week , pH too low for the silvers , and theyre showing the result of that now and slowly dying one by one , possibly due to starvation because they aint eating cause they dont feel too good I wonder why its only affected 4 out of 20 silvers , and those being by far the biggest of the lot ( IM embarressed to tell you all how small my SMALLEST silver perch are ... )

Author:	Troutman [ Dec 6th, '09, 20:20 ]
Post subject:	Re: mystery silver perch deaths ....
I recon it could be stress related. I have found that Perch, particuarly as they get bigger dont like being moved. I (and I know of several others) who have moved Perch around have often lost a percentage of them for no apparent reason. The deaths usually occur a week or two after the move has occured. How did you go about catching them out of their original enclosure??

Author:	RupertofOZ [ Dec 6th, '09, 20:29 ]
Post subject:	Re: mystery silver perch deaths ....
Probably a bit of all those things Boris.... and as Troutman says... netting/moving Silvers can be really stressful... Moving them in an already weakened state... albeit that you might have had to... probably just finished them off... Leave the rest to rest & recuperate... they'll probably be fine...

Author:	Chappo [ Dec 6th, '09, 20:42 ]
Post subject:	Re: mystery silver perch deaths ....
I'd be very interested in knowing how the PH got down so low.

Author:	Rick [ Dec 6th, '09, 20:59 ]
Post subject:	Re: mystery silver perch deaths ....
I lost small Silvers back in the end of Sept for no apparent reason. Trout in the FT Silvers in the sump. My PH was at 6 and shell grit, even ground shell grit was making no improvement. I used dolomite in the FT and buried in the GB's, before and change happened and that took yonks. After feeding a higher protein diet, the silvers stopped dying and the Ph gradually made it back to 7. One would have to assume that both of these factors had some bearing. I pruned tomatoes at the time the silvers died. Someone else lost fish at the same time as pruning tomatoes. Coincidental?? Does tomato stalk juice contain something bad to Silvers??

Author:	Chappo [ Dec 6th, '09, 21:07 ]
Post subject:	Re: mystery silver perch deaths ....
You bet ,, tomato plants are VERY poisonous

Author:	Boris01 [ Dec 6th, '09, 21:18 ]
Post subject:	Re: mystery silver perch deaths ....
well we just pruned a bunch of tomatoes .... ripped out a mountain of celery too I'd be very interested to know how the pH got down that low aswell Chappo . Ive gone through everything I can think of and there doesnt seem to be any apparent reason it should be so low Troutman , I caught em with a net , into a bucket containing water from the tank they came in , then let the bucket float in the new tank for a while gradually adding water from the new tank . it WAS about 2 weeks ago , so this could be the percentage deaths that usually occur OBO the food theyre getting is 4mm Silver Perch pellets from Glen Forrest stockfeeders 33% protein 8.5% fat 2.4% crude fibre 1.4% calcium 1% phosphorous theyve been fed on it ever since I got em off you from that run you did last year ( same stuff , not same bag ) So I need to find a way to keep my other system at a constant pH of 7.5 - 8 , If the silvers prefer the slightly higher pH that really suits the capsicums Ive got - I found that capsicums do really good at high pH ( well , mine do for some reason )

Author:	Boris01 [ Dec 6th, '09, 21:21 ]
Post subject:	Re: mystery silver perch deaths ....
lucky we only pruned a few of the plants then I dont think that would have been the cause though , as the trout werent / arent affected ( although , if the silvers were weakened already due to the low pH ... )

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