Aquaponics Update 4-16-13

Quick update with a picture.  🙂

I got semi-scientific today, and did my first fish weigh in.  I have approximately 7 fry/fingerlings/fish that weigh approximately 3 grams (0.1 ounces).  The rest of them are still even smaller, and the scale that I have can’t actually calibrate that low for them.  I am continually bewildered why the growth rates are so random.  All of these fry are from hatch dates that are within 2 days of each other. Both cohort groups that I took from were hatched March 2nd and 4th, 2013 – so they are both approximately 1.5 months old.  The only hypothesis that I can come up with at this point is that perhaps one of the group were from a hybrid mother, hence with some random genetics of generation 2 from a hybrid cross, while the other cohort was from 2 purebred parents, hence being a generation 1 hybrid, with the hybrid vigor potential that comes with that cross.

So, the larger group are approximately 1 inch long at this point, with the others trailing from somewhere between a 1/2 inch to 1/4 inch.

I haven’t really made any adjustments to the physical setup since last post – though I am overdue for making a tank cover with screen, in the eventuality that I have any jumpers in the groups.  At this point, my thought on that front is to go really cheap and use angle cut and glued PVC from scrap, to make a open rectangle that will gravity sit over the top of the tank.

On the plant side, I have 5 kohlrabi going, and 5 lettuce heads going.  So far, I’m pleased to see that all of the plants seem to be healthy, with only fish waste nitrates and minerals for their growth.  I’m still having a beast of a time getting the tank water quality to clarify, but am also considering a secondary experimental solids filter more along the lines of a sand filter.  More on that when it gets completed.

All things considered, and with the knowledge that I’m not yet testing the water (haven’t invested in a water test kit quite yet), I’m really pleased with the growth and preliminary success of the system.  At some point in the general future, I’m going to acquire some testing kits, to make sure that some of my assumptions are correct.  The first assumption I am working with is the general rule of thumb that the upper limit for a commercial, well circulated tank is you cannot exceed 0.5 pounds of fish to 1 gallon of water.  Hence, my largest eventual tank (20 gallon) will hold 4-5 fish at maximum growth before they graduate into fillets.  However, at current specs, I have massive amounts of room, as the total mass equals approx 30 grams (rough estimate), or one ounce, with my maximum total tank weight of fish would be closer to 2.5 pounds.  I am treating the formula with a lot of wiggle room, because I am nowhere near a commercial scale when it comes to water quality, and I really don’t have any desire to asphyxiate my fish from lack of oxygen.

More to come…

Categories: Aquaponics

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