Anytime you embark upon a new endeavor, there are always a multitude of decisions to make. Aquaponics is no exception. Some decisions are made for you, such as where the garden will be (on our south facing garage wall - it gets the most sun of any vertical surface around), and what size it will be. Size is, of course, limited by space and funds available. :-)
Building materials were determined by cost. The use of vinyl gutters, for example. And we already have a 40 gallon translucent tub that will work perfectly for the reservoir and fish tank. (Clear glass tanks would have allowed too much sun to reach the fish and cause the water to heat up too much for their comfort. I could have covered a glass tanks sides -we have several tanks around here - with waxed paper to do the same thing, but why bother when we have a perfectly good tub?)
Substrate (the stuff that will take the place of soil for the plants) was determined by what was available at Home Depot when we visited yesterday. Red Lava Rock. Relatively lightweight, porous, with lots of surface area for nitrifying bacteria to live upon.
**Science warning - Feel free to skip this section if you're not really interested in the science details of what we're doing ***
Every time a fish breathes, pees or poos, every time a piece of food, fin or scale falls to the bottom of the tank and rots, ammonia is produced. Ammonia is just as toxic to fish as it is to humans, burning their skin and gills until they literally suffocate in their own waste. Luckily, a group of bacteria including Nirtosomonas, LOVE ammonia, and gobble it up. Of course, everything that eats poops, so these bacteria produce their own waste, called NitrItes. (Yes, I meant to capitalize the I. You'll see why in a moment.) Nitrite is almost as toxic to the fish as ammonia. Luckily, another group of bacterial janitors come into play, including Nitrobacters. These consume the nitrItes and produce nitrAtes (see why I'm doing that now?) Nitrates are, basically, fertilizer. Wait, fertilizer? Is that why this works with plants? Yep. Also why over-crowded, over-fed, under-changed aquariums get overrun with algae. Algae are tiny, tiny plants who live on light and nitrates. Nitrates, in low levels (under 40 parts per million) are generally considered safe for most fish. In a normal aquarium, nitrate levels are kept in the safe range by doing water changes. In an aquaponics system, the plants consume the nitrates (fertilizer, remember?) and return clean water to the fish. When it works right, it's a beautiful thing!
***End Science section***
So many of our decisions have been made for us, or were made easy by distinct boundaries. What plants we grow will be similarly limited - by space, availability, appropriateness to the system, and by what we enjoy eating.
But one decision isn't quite so limited: what fish to use. Raising fish for food isn't really an option. There won't be enough time to raise any to an edible size. And, to be honest, I'm not certain I could really kill and eat a fish I've cared for that long. I've had too many years of keeping them as pets. And the size of our tub limits any of the really big fish, like Pacu, walleye or pike. Or Koi. What many people don't realize, is that, over time, koi reach almost 3 feet in length. As much as I love them, especially butterfly koi with their long flowing fins, I can't justify keeping them in so small of a container. If I'm going to have koi, I need a pond. A BIG pond!
Frequent temperature fluctuations rule out many delicate tropical fish. And many of my favorites, like angelfish, just don't show off well when they're stared at from above.
But one type of fish has been bred for just these conditions - goldfish. And here's my confession: I really love goldfish. Bright colors, flowing fins, engaging personalities (yes, goldfish are actually intelligent enough to have personalities, if they're kept in large enough environments.). What's not to love? Other than the fact that they ALL - every single variety - get huge. At least 12 inched from mouth to the base (not the tip) of their tails. Some reach 18 inches. But, with the water flowing through the system, our tub will be big enough to support at least 6 to start. I have a 75gallon that I will bring the fish into during the winter. So it looks like goldfish are the choice. But what kind? There are two major divisions of goldfish - single tailed and double tailed. Single tailed are the ones often referred to as "feeders" or "common" - they have a torpedo shaped body and a single tail fin and come in regular (comet) and calico (Shubunkin). Double tails are commonly referred to as "Fancy" and are known for their squat, stubby bodies and large, flowing triangle shaped tails. There are more varieties of double tails than singles, including Ryunkins, Pearlscales, Lionheads, Orandas, Black Moors and more. Combining single tails and double tails is generally not recommended. Single tails tend to out-compete double tails for food, and bully them a bit.
So the question really is, single tails or double tails? Single tails tend to be a bit hardier, but grow to 18 inches. Double tails tend to be a bit less hardy, but generally only reach 12 inches, and come in a greater variety of shapes and colors. Double tails tend to cost more, too.
In all honesty, except for a few exceptional Shubunkins and Comets, I tend to prefer the double tails. And they do look better from above (that's how they were bred to be looked at) than the single tails. So I think we'll be going with those. Although I'm still a little tempted to throw a ton of gorgeous guppies in there and see how they hold up. Or platies. Or other livebearers, Then we'd have a self-populating group. Of course, then we'd have to have something in the tub for babies to hide in so they don't get eaten. Every additional thought brings more parameters to think about. Smaller fish would be easier to care for through the winter, and be more comfortable in the 40 gallon tub. But goldfish would be able to stay out in the tub deeper into the fall without requiring any additional heat, and be able to go out earlier in the spring.
Hmmmm. This is going to take more thought. Stay tuned.
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