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Dr.Kada Narayana Murthy
Assistant Manager-Technical at Growel Feeds Private Limited
Asked a question last year

In Shrimp RAS Design, how are molted shells handled? Is it necessary to remove them ? If so, what kind of changes are to be made in the design (round and raceway tanks) ?

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it depends also on the size of screens used to cover the stand pipes  you use at their various stages...at times the screens can be too small and moults have to be physically taken out....moults can block the screens on stand pipes if you have a mass moults occurs.....I think these types of tanks used for fish can work well with RAS prawns especially for getting rid of moults, waste etc.....a passive energy efficient way of getting your effluent and waste out....if prawns get sucked up there are perforated screens that will stop the prawns at the top and all you have to do is scoop them up and throw them back in the tank...you wont get heaps of  prawns sucked  up in the pip unless you turn the incoming flow up !

In Shrimp RAS Design, how are molted shells handled? Is it necessary to remove them ? If so, what kind of changes are to be made in the design (round and raceway tanks) ?

 

Dear Dr. Kada,

Penaeus vannamei molt every four days until they are about 2 g, molting less frequently as they get older...

https://www.researchgate.net/profile/Ercument_Genc/publication/261525171/figure/fig1/AS:296910708592645@1447800437485/Molting-and-live-weight-gain-of-Litopenaeus-vannamei-fed-on-diets-containing-MOS-and.png107

... depending on the (1) prevailing environmental culture water parameters including climatic condition and the  (2) health status of the shrimps, with Penaeus monodon molting less frequently than Penaeus vannamei in general. 

https://link.springer.com/article/10.1007/s10499-011-9437-957

In ground-elevated indoor shrimp RAS, ROUND TANKS are cheaper to construct using only lightweight materials compared to above-ground raceways-type encasements.

https://www.youtube.com/watch?v=eWyahblhLr455

By forming a slightly slanted bottom towards a sump pit at the center along with the positioning of the RAS return-lines along the wall of the round-shaped tank whether clockwise or counter-clockwise, one can create a centrifugal current that can eventually concentrate the molt casings, fecal debris, and detritus to the central sump where these can be sucked out either by gravitational force or via a pump suction-line.

https://www.youtube.com/watch?v=mCGytr7Jkt863

Or with a large ground-excavated shrimp RAS, whether a ROUND POND, HEXAGONAL POND, or SQUARE POND, a larger central sump can be installed for the same purpose with greater efficiency than with ground excavated rectangular pond.

https://www.youtube.com/watch?v=4ydaroAhu1g55

Kind regards,

Nelson

Sergii Vilenovich
independent consultant on technologies for growing shrimp at RAS

patent for shrimp shell remover In RAS system

CN201811548991.1

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