From: Kenneth Betts [mailto:kwbetts2@gmail.com]
Sent: 13 March 2012 14:48
To: William Leschen
Subject: Re: [Sarnissa] Dear members,
Here are some pictures of the hand held graders that I made. Sorry the first pictures were too large.
Ken
On Mon, Mar 12, 2012 at 1:33 AM, William Leschen <william.leschen@stir.ac.uk> wrote:
Thanks Kenneth
But please could you send smaller photos - file size max 500kb - 2M each is too much for the forum - then please resend your message
I hope someone also sends in some photos of normal bar graders - these work well and easy to pivot up and down so operator doesn’t have to lift whole weight of fish each time
Best wishes Will
From: Kenneth Betts [mailto:kwbetts2@gmail.com]
Sent: 11 March 2012 14:18
To: sarnissa-african-aquaculture Mailing List
Subject: Re: [Sarnissa] Dear members,
Here are some pictures of the hand held graders that I use.
Kenneth
On Sat, Mar 10, 2012 at 12:53 PM, Nazael Madalla <nmadalla@googlemail.com> wrote:
Dear Kenneth,
Your homemade graders sound interesting. Can you please attach a photo.
Cheers!
Nazael.
On 10/03/2012, Kenneth Betts <kwbetts2@gmail.com> wrote:
> For my farm, which is only small, I made hand held graders out of blue
> plastic barrels. I cut each 80 liter barrel in half to make two "baskets".
> I cut hand holds in them. I a local tooling shop to make a set of iron
> hoops of graded sizes (20 mm, 25 mm, 32 mm etc) which I heat in a fire and
> then melt lots of holes in the bottom and sides of the baskets, each basket
> with the same size hole. Three people working with these baskets can sort
> thousands of fish very accurately in a few hours.
>
>
> On Fri, Mar 9, 2012 at 11:19 AM, Patrick Wood <patrickjwood@yahoo.com>wrote:
>
>> **
>> How about using people to hand grade? Is there not a prescribed hand
>> method and accompanying research on labour/size fish/grade rate?
>>
>> Karen L. Veverica wrote:
>>
>> Ernest, I made a grader locally (in Ghana) but had to leave it at a farm
>> and they decided they did not wish to try it; it is still there. It is
>> supposed to be handed over to another vary large farm for trial but I
>> doubt
>> this has happened.
>> Graders can be expensive if you want them to work well; they can be
>> home-made but often are not made well-enough to be consistent.
>> Also.... even if you have a good grader, if it is used wrongly, it will
>> not grade. The density of the fish in the grader is important; if too
>> few,
>> the fish do not wish to swim out; if too many, the fish can't get out. If
>> you create a water current to encourage them to go out, they may end up
>> jumping out. For grading tilapia fry, I like to have a grader with good
>> enough freeboard (about 30 cm) so the fish do not jump out without having
>> to put a cover on.
>>
>> To better assist the others who will no doubt wish to respond, please give
>> the numbers of fish you are wishing to grade at a time and their size. You
>> mean tilapia, right?- these are best graded through the sides of a grader;
>> for catfish, graders should have the bars on bottom. Most graders have
>> bars
>> on 2 sides and bottom but people making home-made graders should know what
>> is most important for their fish.
>> Grading is rather important when it comes to getting better feed
>> conversions and when it comes to trying to get fish large enough so they
>> do
>> not swim out the mesh of your cage.
>> We use the floating "basket graders" if we have fewer than 10,000 fish to
>> grade. When we have a lot, we use a bar grader/crowder in a large tank.
>> You have to give the fish time to grade.
>> After you tell us the fish size you wish to grade,I am sure several of us
>> can send you photos.
>>
>> Karen L. Veverica
>> Department of Fisheries and Allied Aquacultures
>> International Center for Aquaculture and Aquatic Environments
>> Auburn University, Alabama, USA
>> office: +1-334-844-4667
>> cell: +1-334-332-1560http://www.ag.auburn.edu/fish/
>>
>>
>> On 3/8/2012 12:08 PM, Ernest Abiew wrote:
>>
>> Could any member help me with this information. I wanted an information
>> on a simple and a practical method or methods of grading fish that can
>> easily be used by farmers in Ghana.
>>
>>
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>>
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>
>
>
--
_________________________
Nazael Madalla, PhD
Lecturer (Aquaculture)
Department of Animal Science and Production
Sokoine University of Agriculture
P.O.Box 3004
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Tanzania
Mobile:+255 769 220 212 or +255 719 489 171
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