Aquaculture is the growing or propagation of finfish, shrimp, lobster, oysters, algae, and other aquatic organisms for food, education, fun, or profit. In 1994, aquaculture accounted for 20% of the worldwide consumption of these organisms, and this amount is expected to increase to 25% by the year 2000.
Aquaculture offers students a world of learning opportunities. Many traditional courses including biology, applied mathematics, zoology, chemistry, physics, marketing, sociology, business, agriculture, and health can be structured around your "think tank." Practical lessons in volume, density, friction, weight, gas-liquid dynamics, conversion ratios, pollution concepts, and most importantly, responsibility, may be gained also.
A hands-on classroom aquaculture system generates new enthusiasm in both teacher and students. Every day, the class must make sure the fish are fed (usually overfed), the water chemistry checked, the filter cleaned, and a little fresh water added. This responsibility and excitement brings energy to the whole class and puts a smile on the teacher's face.
What's the catch? Well, other than an occasional "floater" or some spilled water on the floor, there really isn't one. Classroom aquaculture is here to stay, and you can set up your own system easily and inexpensively. For your new aquaculture system to be a success, it must have a culture tank, a method of solids removal, a biological filter, a method of oxygen introduction and carbon dioxide release, a water-chemistry monitoring schedule, enough supplies to maintain the system, and a good manageryou, the teacher.
Culture Tank
The first piece of equipment to plan for is the culture tank. For strength and durability, it should be constructed of polyethylene, fiberglass, or steel, with a food-grade liner insert. Plan so the tank fits through your classroom door! A round tank is the best choice because, given the proper drain location and a counterclockwise flow, it is self-cleaning. A bottom sloping slightly towards the center drain enhances the tank's ability to self-clean. For educational purposes, tank depth and diameter should be at least 24 inches, and not more than 40 inches. The overall size of the tank should be regulated by available classroom space, but it should be big enough to enjoy and small enough to control.
Clarification
Clarification, or solids removal, is one of the most important components of the recirculation system. Solids in an aquaculture system consist primarily of uneaten fish food, fish feces, and algae. Remove these solids quickly; otherwise higher levels of ammonia and lower levels of oxygen occur. Clarifiers physically trap or detain solids in some type of collection basin that does not allow them to pass further through the system. Once a day, or every other day, these solids must be drained and removed from the system. This waste is an excellent fertilizer for gardens or hydroponic setups, as it contains a high amount of nitrogen.
