Macrobrachium rosenbergii Goes To School

Remember last summer when I spent a week down at Harbor Branch Oceanographic Institute (HBOI) and every post from Fort Pierce sounded something like this, "I HAVE DIED AND GONE TO AQUACULTURE HEAVEN!!"

At the time, my students and I had assembled a very simple recirculating aquaculture system (RAS) using a 300 gallon livestock tank and some pvc. There was no budget for such nonNCLB educational experiences, so I wrote a small local grant and won $200. That almost covered the cost of the tank and pvc pipe.
My wallet covered the rest.

The money ran out just about the time the school year did, so we did not stock the tank with any fish that year.

While I was at Harbor Branch last June, picking the brains of their best and brightest, I wrote another grant and won $500 from HBOI to continue my project.
Thank you HBOI!!!

Back at school in a new year, I went through the state regulatory process for possession of restricted species, because I fully intended to grow tilapia, a fish I used to grow at home in my own backyard RAS. There was a little delay due to the inspector's busy schedule, but he did come by to make sure we were in compliance and gave me some useful advice about finding tilapia fingerlings close to home.

At some point during the Christmas break, I decided to go with giant freshwater prawns ... Macrobrachium rosenbergii. They had fascinated me for a long time and since they were not a restricted species, we would have more freedom to move them around.

So, I contacted Craig Upstrom at Aquaculture of Texas. Craig runs a Macrobrachium hatchery and he turned out to be one heck of a nice guy. He gave me lots of advice about the prawns and hand picked a nice mix of larger juveniles plus some very tiny post larvae stage prawns.

I waited until after the FCAT so the high stakes testing would not be disrupted by shrimpnicity and then made my order using my grant money from HBOI.

When I told the kids that we would finally be getting livestock for our aquaculture system they were really excited. The thing had sat there bubbling away near the classroom entrance all year and at last, something would be swimming around in there.

On the day of the delivery, I received an email that said the shrimp were aboard a Fedex truck in Gainesville that morning. I shared that with the kids and they stopped by all day between classes to see if the shrimp had arrived.

Finally, at sixth period, my planning period with no kids present, the Fedex truck pulled up to the office.
The secretary, who I had bugged about 5 times that day with "Are they here yet?", called and told me, "We have sushi!"

I was down there in a flash!

The shipping container and it's precious cargo sitting on my messy desk.


I floated the bags of baby prawns for about an hour while the temperatures evened out just like you do when you buy a tropical fish from the pet store. The L-shaped pvc pipes in the tank are airlifts that create a gentle circular current and aereate the water.
A circular current carries waste and uneaten food to the center where it can be easily siphoned out. We do that once a day.

The bucket hanging in the tank is full of bioballs and biocylinders with an airstone at the bottom to create an uplifting current. The students drilled holes in the bucket to allow water to flow in and through it.
It's a very simple biofilter and we plan to upgrade it, but for now it's where the bacteria (that would be "special store bought" bacteria) do their denitrification.


What a beauty! These shrimp have fascinating social dominance levels and they get BIG!
GOOGLE them and check that out for yourself.



Most of our shrimp (about 75) are juveniles in the 5 cm range. They arrived in great shape and seem plenty frisky and active. Craig tossed in some tiny post larvae shrimp also and they are about 1 to 1.5 cm.

The picture above shows a trio of juveniles patrolling around some food pellets. The little white crescents to the left are a few post-larvae that didn't make it in the shipping process. They were consumed by the juveniles that first night.

Prawns are territorial, so one of the things the students will be doing is building a few structures of pvc and plastic mesh to place in the tank. These crustacean condo's will increase the available surface area for the shrimp and allow them to spread out. This reduces cannibalism and increases growth rates.

I'll keep you posted on our progress as the kids and I learn the ins and outs of farming shrimp.