September 25, 2014 After much research it appears that concrete in general can be safe for fish and plants, provided the system sits with water in it, changed periodically, for up to a month or so. Concrete can be seen hosting fish and plants all around Thailand, including here in Bangkok, so it was always known that it was possible.
Instructable tutorials suggest cardboard with duct tape between it and the concrete.
The design will probably look like something pictured to the left but a bit smaller, however the final, exact design will be determined by the cardboard I can find. The post office here most likely has a variety of boxes that can serve this purpose. Remember, the first box holds the concrete in, the second box holds the void within the finished shape.
Potential Fish and Plants
Snakeskin gourami fish turn out to be a very popular and easy fish to take care of in both terms of hobby fish keeping and aquaculture. Because of their docile nature, they make good additions to community tanks which means other fish can be included in the aquaponics setup. Zebra fish are a possibility, so are freshwater shrimp, and some perpetually breeding varieties like guppies and swordtails.
It may be nice to use fish that are all indigenous to Thailand (where Helios Labs is located) so that the set up can double as a research microcosm as well as an experimental food source.
For plants, ultimately the goal is to grow enough for tomato sauce, herbs, and a salad. Even before the aquaponics system is set up, I've already investigated an indoor system to run in parallel ... indoor, perhaps hydroponic mushrooms. Hay mushrooms found here in Thailand, and Italian-style portobellos (agaricus bisporus) are possible varieties that can be grown.
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