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Wanted—Specifications for Shrimp Nurseries
Joseph Paul (email@example.com): I would like information on the following aspects of shrimp nurseries:
• Dimensions (length, width, height)
• Materials for Making Them
• Stocking Densities
• Stocking Sizes
• Growout Period
For example, if a cement tank (15m x 15m x 1.5m) is used as a nursery, how many days can two million PL-10s be held there before stocking them in growout ponds? What should I feed them? What kind of aeration should I use?
Any answer, in part or full, would be appreciated. I would also like to hear about your experiences with nursery tanks. If you know of any reports, manuals or publications that deal with this subject, please let me know how to find them.
Eric De Muylder (firstname.lastname@example.org): You should try to keep your biomass density below 3 kg/m³. So if your tank is 337 m³ and you stock 2 million, you will reach 3kg/m³ when your shrimp are 0.5 g. You should be able to reach 0.5 g from PL-10 in 3 to 3.5 weeks.
Aeration should be with aerotubes or similar equipment that produces fine bubbles. Pipes with holes drilled in them might be cheaper, but will consume 4-10 times more air and electricity.
It’s important to learn how to transfer the shrimp from the nursery to growout.
You should use high quality nursery feeds because there are no natural feeds in nurseries.
If you know how to work with bioflocs, you don’t need to change your water.
I personally like to start feeding with algae (live, paste or freeze dried) and then add Artemia during the first couple of days. After a week, bioflocs will develop. The first time you do this, it will be difficult, but thereafter, you can inoculate your water with water from the first tank, where bioflocs were already established. This helps to control ammonia.
Giovanni Chasin (email@example.com):
1. We are talking about nursery “ponds”, right? Nursery ponds vary in size, depending on your circumstance. You might have a small pond that you can use. You might have a lot space to build a new nursery. You might need a big nursery if you have a big farm, or if use high stocking densities. It’s best to keep your nursery pond between 0.1 and 1 ha. If your using nursery tanks or raceways, they can be smaller than 0.1 ha.
2. Nurseries can be any shape, but round or rectangular ones are preferred. Construction materials can also vary. You can use earthen ponds, ponds lined with HDPE/PVC, or concrete or fiberglass ponds.
3. Stocking density can range from 200 to 1,000 PLs/m2, depending on the system you choose—higher in small well-equipped ponds and lower in big earthen ponds. PL-10s are considered to be a small size for stocking.
4. The growout period normally ranges from 30 to 45 days, depending on your stocking size and density, salinity and the size juveniles you prefer to transfer.
5. Feed with 50% protein crumble at the beginning and then switch to a 1.8-2.0 mm pellet. I used to feed just a 2.0 mm 35% protein pellet from the beginning.
6. In large ponds, aeration will depend on your final biomass; in small nursery ponds with high densities, your have to carefully monitor your oxygen levels. Normally, paddlewheels are all you need, but there are a lot of other aeration options out there.
7. Stocking 2.0 million PLs in a 300-m3 cement tank (15m x 15m x 1.3m) will represent about 7 PLs/L. This is a good density to permit rapid growth of PLs. You must carefully manage your feed regime and water quality variables. If you prefer to keep the animals for longer than 30 days, you may consider biofloc technology to supplement your feeding regime and to stabilize your water quality. Keep in mind, that it takes some experience and expertise to manage biofloc nurseries.
8. Learn as much as you can about transferring juveniles to growout ponds.
Diego Maia (firstname.lastname@example.org):
Everything depends on your intentions. What size PLs will you be stocking? How many PLs do you need?
Another thing to consider is the experience of the people who will be managing your nursery.
A biomass 3-4 kg of PLs/ m³ or more can be achieved, but for someone who has never had experience with this process, it would be wise to start with a lower biomass than that.
Aquaculture Magazine recently published an interesting article on: Nursery Phase in Shrimp Farming: Benefits Beyond SEM.
You can also find some information from a presentation by Mr. Carlos Ching (Nicovita Feeds) at FENACAM 2014 (Brazil, November 2014).
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