Backyard Aquaponics
A place to discuss aquaponics

I think Ive posted this query before , but here goes

on and off ( on again now ) , Im losing 1 silver perch fingerling a day , from 2 - 5cm . the smaller dead ones have scuked in stomachs , the bigger dead ones not.

no signs of stress ( apart fro mthe wide open mouth after death ), no scratches , no flashing , no algae
pH is 7 , temp is fine , DO is at around 80% . ALL water parameters are fine

in an adjoining tank ( same system , same water , seperated by a stainless steel mesh over a 50mm pipe ) are 40 20cm+ silvers , they eat the same food ( not crushed up ) and none have died since a few at transefer 4-5 months ago

There seems to be nothing wrong with the dead ones ( apart from being dead ) although theyre kinda hard to autopsy at this small size

My ONLY idea of whats going wrong is that theyre getting wierd / abnormal growth rates in some parts of their guts or something from eating the crushed up skretting trout pellets . Duckponds are eating crushed up low protein silver food from glen forrest and none have died - leads me to beleive the food is at fault , not that its mouldy / off / old cause all other silvers in this system and the other are eating it fine

so , fish people - is high protein food BAD for my fingerlings ?!

oh , btw - just salted to 3 ppt

although it may be higher than that from residual salt that I put in a while ago , o way to really tell at the moment - its either 3ppt or higher , Im sure the celery will suck up any excess

Humm... wouldn't tend to think so... small fingerlings are often fed a slightler higher protein feed anyway... and usually 4-5 times a day...

2-5cm is a small fish though... not much above a crumble stage... a #1 pellet at best... just what size are you crushing the bigger pellets down to... and how often are you feeding....

Try going to a "dust"... and 4-5 times a day...

Maybe they either can't take the crumbled bits... and/or they're not getting enough...

As I said before... swings in tank temp around this time of year can impact on tiny fish... what's your water temp at the moment overnight...and during the day...

And how much has this changed in the last few weeks??

Im crushing it in a mortar and pestle to a dust , feding 2 - 3 times a day

tank temps are pretty stable - no real swing between day and night , but it is slowly dropping now that the weather has turned

its possible theyre not getting enough food , which was what I thought after the last few deaths , so I upped the feed and now lost one of the bigger ( 5cm+) ones today

also possible that the food is too old - not off but no good for small fish , maybe the bigger / older silvers have stronger stomachs

I'm hoping t IS that they cant handle the food , if not it means I may have a disease or something ( rat poop ? dead roach ? ) and the bigger silvers are tough enough to handle it

Im thinking that with the hit of salt , if none die for a few weeks I'll know its a disease , if they keep dropping dead I'll assume its the food

actually , now that Ive said that , I'll up the food a heap and see if that works - the system can handle a fair bit of dumped food & Ive got a month to clean it up before trout if I have to

wouldnt starving silver perch fingerlings take bites out of the runts when they get too hungry though ?

My tiny fingerlings were on 4mm skretting from day 1. They just nibble at it until it fits.

direct contact from fish to fish spreading a disease ?
This lot of fingerlings cant get through into the adjoining tank , maybe thats why the silvers next door to them are fine

Pellets with a high protein content can cause problems in Silver Perch like liver dysfunction and cause excess body fat. However, I would have thought this would only occur in older fish and not fry or fingerlings. If its a problem with your food it must have deteriorated somewhat. How old is it?? What size pellet is it??
Why dont you try feeding the Glen Forest stuff for a while and see if things change.

Don't go berserk... although fingerlings are fed more frequently, and slightly higher protein... they're fed a dust or small pellet and a % of body weight... which might mean that you don't have to feed much more...

Just spread the feed across more feeds/day... with a smaller size... be guided by what they'll take... and don't be surprised if they take a day or two to get used to the new routine...

We have 500 young silvers that are fed crushed up barra pellets and we haven;t had any deaths that I know of... I think Faye may have said she saw one dead fish, but that is the only one we have seen.

All my fish trout, silvers, jade perch, and goldfish, get barra pellets
I only buy 6mm and put them through a coffee grinder to suit

My silvers are getting barra pellets (whatever Joel is selling at the moment) and have been for most of the 2 weeks they've been here - no obvious problems and no deaths.

I do throw some duckweed in most mornings as well and they seem to clean that up every day (and they leave any azolla).

well , more food today = 3 more dead

Im going to assume its the food , stop feeding and see if any more die over the next few days . if not then Ive got an excuse to go shopping at byap

( as if I need an excuse )

Maybe I had better be careful then.

I have been feeding my silvers crushed trout pellets since some time towards the end of last year when I heard they needed a higher protein diet when small. Now they are getting 6mm trout pellets whole as I still have some trout pellets left over.

At what size might I expect problems??

Silver Perch feed varies from about 30-38% protein... trout feed might be anything from 40-50%