Alternate Fish Food

[Jeff S]

I hear Tilapia eat anything. Can I safely feed mine vegetable leaves to supplement their food? If so what types are best?

 

[Alex Veidel]

Yes, theoretically you can feed them vegetables. Though some tilapia can be picky eaters, apparently. It often depends on what they've been trained to eat.

[Jeff S]

I've thrown a few leaves from my tomato and bell pepper plants in and they do eat them....not right away but overnight. I was thinking about visiting the local supermarket and get some old greens either free or cheap.

[Alex Veidel]

Yeah, don't throw tomato plants in there. They're poisonous to fish....And since bell pepper plants are also nightshades, its probably not a good thing to use either. Feed them leafy greens (think lettuce).

Careful about supermarket produce. Greens can be covered in pesticides. And most of them are absorbed into the plant itself, so they can't be washed off. Make sure you go organic.

[Scott Roberts]

Organic doesn't mean no pesticides. In 2011, over 20% of organic lettuce in the USA had pesticide residue, including Spinosad, Pyrethrins, and azadirachtin.

[Glenn]

I have second year asparagus shoots coming up iin a wicking bed. I couldn't resist seeing how trout fry and fathead feeders took to it. So I chopped some into eighth and quarter inch pieces and they all took to it quick. I didn't really want to share more of it and certainly not until next year. The little dears will have to wait in line.

[Rich File]

Spinosad is a natural bacteria, in small doses it won't hurt aquatic life.

[Glenn]

Spinosad insecticide is based on a compound found in the bacterial species Saccharopolyspora spinosa (S. spinosa).

Spinosad has high efficacy, a broad insect pest spectrum, low mammalian toxicity, and a good environmental profile. This is a unique feature of an insecticide, compared to others that are currently used for the protection of grain products.

Spinosad is considered a natural product and approved for use in organic agriculture by numerous national and international certifications.^[

Spinosyns occur in over 20 natural forms, and over 200 synthetic forms (spinosoids) have been produced in the lab

Spinosad insecticide contains a mix of two spinosoids, Spinosyn A, the major component, and Spinosyn D (the minor component), in an approximately 17:3 ratio.

Ref. Wikipedia  http://en.wikipedia.org/wiki/Spinosad

In my humble opinion, this may seem safe for ordinary use in garden and marine settings. BUT there is some debate about the toxicity in honey bees and no known studies of effects in Aquaponics if allowed to accumulate long or short term. Thus, I believe in minimal use where absolutely necessary and along with a robust regular removal of solids build up and water changes. And in keeping an open eye out for manufacturing changes that might bring more controversial synthetics into the mix with additional significant markers for long term mutagenic effects in mammals..

[Alex Veidel]

Same conclusion here: Spinosad has a pretty low effect on water quality. That's really interesting to know about the potential effects on honey bees.

And I also agree with you Glenn about using it minimally. I really think pesticides (even if they're "healthy) should be limited to use when only absolutely necessary. They tend to throw off the insect life balance of a garden environment. Honestly as of right now, I think adding anything beside fish food and compost teas to your aquaponic systems should be avoided as much as possible.

Glenn said:

Spinosad insecticide is based on a compound found in the bacterial species Saccharopolyspora spinosa (S. spinosa).

Spinosad has high efficacy, a broad insect pest spectrum, low mammalian toxicity, and a good environmental profile. This is a unique feature of an insecticide, compared to others that are currently used for the protection of grain products.

Spinosad is considered a natural product and approved for use in organic agriculture by numerous national and international certifications.^[

Spinosyns occur in over 20 natural forms, and over 200 synthetic forms (spinosoids) have been produced in the lab

Spinosad insecticide contains a mix of two spinosoids, Spinosyn A, the major component, and Spinosyn D (the minor component), in an approximately 17:3 ratio.

Ref. Wikipedia  http://en.wikipedia.org/wiki/Spinosad

In my humble opinion, this may seem safe for ordinary use in garden and marine settings. BUT there is some debate about the toxicity in honey bees and no known studies of effects in Aquaponics if allowed to accumulate long or short term. Thus, I believe in minimal use where absolutely necessary and along with a robust regular removal of solids build up and water changes. And in keeping an open eye out for manufacturing changes that might bring more controversial synthetics into the mix with additional significant markers for long term mutagenic effects in mammals..

[Jeff S]

FYI I just discovered if you put 500 1" Tilapia in an IBC covered with duckweed it only takes a fw days for you to lose all your duckweed. Hope I salvaged some healthy duckweed to replenish.

[Scott Roberts]

FYI Spinosad has a 96hr LC50 of 5ppm for some fish. Even duckweed will die at 10ppm. Once in the water, Spinosad has a half life of approximately 1day under direct sunlight.  Since most of us shade our water to prevent algae growth, Spinosad could stick around.  The real worry about spinosad would be if you used it repeatedly, and then rain washed it off the plants and into the water.

[Alex Veidel]

Well, just out of curiousity Scott, I went and did some math for you.

Spinosad isn't just purchased straight up. It's purchased in a formulated concentrate. The concentrate that I use (Monterey) has a spinosad content of .05%. Now, I don't really trust my own math, but I think I've got things correct. If you wanted a spinosad concentration of 5ppm, you would need to add 2 quarts of concentrate to my 600 gallon system. That's literally going out and purchasing 2 separate quart containers of spinosad concentrate and dumping them straight into your system water all at once.

Now, you use about a 4tbsp of spinosad concentrate per gallon of water to create the insecticide spray. And then you apply that spray foliarly, being relatively careful not to get a ton of excess on your media. The crop with the lowest recommended time interval between spray applications was sweet corn, for which they recommend waiting a minimum of 3 days after applying before spraying again. For most crops, it was in the 5-7 day range. Given that spinosad dies off after 1 day in direct sunlight (which was new information to me, thank you for sharing that), I think it's reasonable to assume that the use of spinosad as an insecticide is a pretty safe way to play. Just relatively know what you're doing before adding anything to anywhere.

Btw, somebody please go ahead and check my numbers. I might have screwed something up.....

[Scott Roberts]

Alex - thanks for doing the math. Although - can you check your Spinosad bottle? I'm seeing a concentration of 0.5% for the Monterey Garden Insect Spray concentrate.