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Overwintering with Silver Perch ?? maybe get some koi for winter nutrient output

Discussion in 'Fish' started by benwalters, Apr 22, 2013.

  1. benwalters

    benwalters Member

    Joined:
    Nov 5, 2010
    Messages:
    333
    Country:
    Australia
    State:
    NSW
    City:
    Bowraville
    Hi Folks, :)

    Ive been off the forum for a while and now im interested in getting some advice about overwintering silvers


    I have two systems (sorry about some abbreviations)

    North System - cut down IBC fish tank, with 750 litres , two ibc 'lids' as grow beds, f/d (15:45),

    South system - cut down IBC fish tank, with 750 litres , six 1/2 blue barrels as grow beds, f/d (15:45), attached NFT tube continuous flow

    Each system has approximately 25 silver perch about 2 years old (variable sizes 60-600 gram guesstimate)

    Main intention has been to get fresh greens, at various times this has been working well, had some good tomatoes when the fruit fly arent around, some times ive been too slack to plant out
    haven't harvested fish yet as i haven't figured out how to catch the biggest one without stressing others...........

    Quite possible that i have been underfeeding, but ive had the odd fish fatality and wanted to err on the side of caution




    ISSUES----
    Excessive rainfall diluting nutrients - this has happened a lot

    Cold in winter - Im on the Mid north coast NSW, and being a little inland, water temp have been as low as 5 degrees,

    have over salted a little once or twice after i was worried about fish / some plants really dont like it !!!



    NOW-
    The silvers are interesting in that there is very different behavior between the two FT even thought they are only 1 metre apart

    South lot have gone off their food, and temps have only just dipped below 20
    North system are feeding fine still,

    anyway this is reminding me that there is a few months coming up with temps below 15 and feeding every 2 to 3 days if im lucky,
    when it gets below 10 there is weeks between feeds

    I leave the tank lids open in winter to try to get some heat from the sun

    I did stick a 300 watt heater (under powered i know ) in a tank for a few weeks and maybe got a degree of temp rise ????? i guess this cost $2 day

    The NFT addition seemed to add 1 degree to temp when i stuck that on....

    I sorta not keen to heat but maybe if it is just to keep them going it might be worth spending $X bucks per day for a few weeks if it kept them a bit happier - also the plants cant be too happy with very low root temps ????

    Other options to preserve heat are adjusting the F/D times to / less flood at night, (but the NFT has to run all night i believe)

    Also different feeds like worms and greens are supposed to keep fish eating in lower temps




    ANYWAYS,

    someone suggested that Koi feed at lower temps and produce more waste
    as i am not harvesting anyway , maybe this could be an option , if i had the right setup id be keen for trout but then id have to learn how to harvest them !!!!!

    i sorta like having natives but they dont interact much, they smash the feed, then hide away again
    so any way ,

    apparentlly the koi and silvers can be run together ???????

    anyway interested to hear any tricks, about how to keep fish feeding, and hear other experiences

    post your tank temps below !!!

    temp max 22
    temp min 18

    ill put some photos up after dinner
    cheers
    ben
     
    Last edited: Apr 22, 2013
  2. benwalters

    benwalters Member

    Joined:
    Nov 5, 2010
    Messages:
    333
    Country:
    Australia
    State:
    NSW
    City:
    Bowraville
    hi again , i just googled NFT root temp,
    "For optimal results, the temperature of the nutrient solution should also be monitored. The ideal water temperature is between 68 and 75 degrees F. If the water temperature gets too high, the nutrient solution will not hold enough dissolved oxygen, but if the temperature is too low, the metabolism of the roots is slowed down and plant growth can stall. Some growers like to warm their nutrient solution in the winter................"

    source -
    http://www.pro-hydrotech.com/How-To-Grow-Hydroponic-Lettuce_ep_53-1.html

    this equivalent range in degrees Celsius -20 - 24

    so it sound like i need to find a way to heat up tank !!!!!!!!!!

    cheers
    ben
     
  3. joeyd

    joeyd Member

    Joined:
    Sep 30, 2010
    Messages:
    76
    Hi Ben

    Silvers are a problem in that they lose their appitite when the water temperatures drop. The good thing is that they can survive a wide of temperatures. I also fimd that my murray cod lose interest in food as the temperatures drop. Like you i found the cost of heating prohibitive. I also keep trout and they are smashing their food at the moment. You could also consider buying some yearling trout which would nicely grow out before next summer.

    Cheers

    Joey
     
  4. benwalters

    benwalters Member

    Joined:
    Nov 5, 2010
    Messages:
    333
    Country:
    Australia
    State:
    NSW
    City:
    Bowraville
    Hi Joey,
    Thanks for the idea,
    What sort of water temps have you got there at the moment ?
    Do the trout and silvers get on okay sharing a tank?

    (One thing about where i am is cool nights in winter, 1/2 dozen frosts maybe , but winter days are quite warm , (28 today not that its winter yet), but its not often under 20 for long, maximum wise, North facing block as well, so this leads me to worry about trout in spring.....if i had better temperature records, or a fish tank in a shed..........)

    heres some pics to stop me rambling.......


    IMAG5565.jpg IMAG5569.jpg IMAG5558.jpg IMAG5559.jpg ............



    p.s. 3rd pic is a japanese green called mibuna, similar to mizuna, quick to grow and nice mild flavour.........
    cheers
    ben
     
  5. joeyd

    joeyd Member

    Joined:
    Sep 30, 2010
    Messages:
    76
    Hi Ben

    My water temperature is about 16 degrees at the moment. I keep a separate tank for each species of fish. I guess if you wanted to keep some trout you could combine your silvers into one tank. Your NFT system made out of drainage pipe looks sure like a space efficient way of growing your produce. I have never heard of mizuna is it some type of spinach ?.
    If you are confident that your water temperatures will remain below 20 degrees for the next 5 months you could get (6 to 10) 18 cm trout yearlings they will be ready for harvest before summer. Small fingerlings would not be a good idea as they need a much longer time to grow out.

    Cheers

    Joey
     
  6. silloth52

    silloth52 Member

    Joined:
    Feb 2, 2011
    Messages:
    403
    Country:
    australia
    State:
    vic
    City:
    melbourne
    hi ben
    i have 2 tanks 1*1500lt@1*750lt
    i have 50 silvers and 10 catfish in the bigger f/t and 3 brook trout about 8" long
    in the smaller f/t
    there was 10 brooks but i lost 7 i,m sure it was with the transportation
    last year i started with 50 rainbows about 2" to 3" long in april in the 1500lt f/t and i was smoking and eating them by nov
    my 3 growbeds that are connected to the 1500lt fish tank has been in operation about 18 months produces great veges
    my smaller f/t with the 3 brooks has 1 growbed and the veges are very slow in comparison
    the larger f/t had the rainbows last trout season so i guess the growbeds are still full of nutrients
     
    Last edited: Apr 23, 2013
  7. benwalters

    benwalters Member

    Joined:
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    Messages:
    333
    Country:
    Australia
    State:
    NSW
    City:
    Bowraville
    thanks for the replies guys,
    The trout sound great, i think i would be lucky to keep temps low enough for 5 months, maybe i should start keeping some decent temperature records............and start off with advanced ones sound like the go...

    pretty pissed of with one lot of silvers, haven't eaten for three days or more, may have to check water chemistry, i guess they will get hungry soon or latter , i tried dropping in some worms, but could see what happened due to water turbulence......


    joey - the mizuna / mibuna are great plants they are a brassica that can be used like a lettuce, they have a mild mustard flavor, easy and fast growing

    silloth - like the sound of having a bit of variety, also smoked trout much have been yummy, and having a few tank could definitely help, i will need to harvest some silvers sooner or later to make some room....

    cheers
    ben
     

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