Not only has Hurricane Sandy been through the area but Fall has arrived and with it are much colder temperatures. I still have fish outside and plants growing in the outdoor system but it is about time to shut things down in the next few days and focus on the indoor system. The outdoor system was incredibly successful this year yielding nearly 100 pounds of fish and large amounts of veggies and herbs throughout the season. A lot was learned as the system was expanded and the growing season was expanded to a 6 month period of time. This will be a long post that will focus on harvesting the fish so that you can see the fruits of our labor.
I first want to make the point that in addition to this system providing food it is also a fun way to learn about some scientific concepts. Part of the simple maintenance is that I regularly check the water for Ph levels, Nitrate levels and so on. I keep tables of the results and make the necessary adjustments when change is needed. It is fun to see how minor changes in anything from water levels, to the number of fish or plants can have impact on the condition of the water.
These pictures and Video are actually from the end of September. I knew that cold days were coming and wanted to harvest a number of the Tilapia before it got too cold at night and I ran the risk of losing them. I have worked with 55 degrees at night threshold being the temperature that I wanted to think hard about pulling the fish. Of note is that I left about a half dozen fish in the tank over the past month and we experienced several nights below 40 degrees. While I wouldnt suggest pushing your luck too much im happy to report that though the fish were lethargic all except one survived.
This first video is of catching and then killing a Tilapia. While this is simply the process by which fish are harvested, this may be too graphic for some people so those of you who are a bit squeamish might choose not to watch this one.
After the Tilapia are caught and killed, I take a few minutes and I weigh and measure each fish and record that data. I am tracking growth rates of these fish starting from when they are 1/4 inch fry and ending with being 2 pound, 14 inch mature fish 18 months later. This video shows several fish being weighed and measured.
One interesting thing that you witness when harvesting the fish is that there is a good chance that several of the fish either have recently laid eggs or are carrying fry. Tilapia are mouth breeders so after they lay eggs that are then fertilized, the females then carry the eggs in their mouth until they hatch. In this picture (again might be a bit graphic for some so I am making it small but you can expand) you see that after harvesting this fish I realized that its mouth had been full of eggs.
The other thing you might find is a female who is carrying a mouth full of fry. In this video you see just that. After catching this female and discovering a mouth full of fry, instead of killing it, I moved it (and the fry) into the Indoor system.
After catching and killing the fish the next step is gutting and scaling. This can be a pretty quick process with the right tools. These photos and the video show the end result of this process.