A Community and Forum For Aquaponic Gardeners

food safety question re: source of fish

We have about 8-10 hand sized bluegill and about 4-6 at 3or4". I caught them in a drainage canal in my neighborhood. The canal is rarely stagnant and filled with good filtering plants. Regardless, I know it is full of runoff, so my question is: are the chemicals in the fish going to be transferred somehow to the plants I'm growing? I don't want to eat the fish because I know where they came from, what about the plants I do want to eat?

0 members like this

Replies to This Discussion

Permalink Reply by TCLynx on August 15, 2012 at 8:56pm

I suppose it is possible that there could be some bad stuff pooped out by the fish after you put them into the aquaponics system so if you want to be a purist about it then perhaps some residues from where the fish came from may be in your system but I expect it will be rather dilute.

And keep in mind that the toxic "metals and stuff that builds up with exposure over time" will likely mostly remain in the fish rather than being passed out of the fish into your system. With that in mind, when your fish do eventually pass on, you want to make sure to remove them from your system before they start decomposing and releasing any of those negative things into your system.

Permalink Reply by JRComito on August 16, 2012 at 8:25am

Thanks for the ease of mind. My wife and I were discussing it, and we came to the conclusion that any of the ickies would remain in the tissue of the fish. It is nice to hear that we were close from someone with experience. What about the plants though? Will the uptake of any of the ickies be harmful for consumption or will the plants metabolize them out? I don't know if metabolize is the right word, but I think you can get the idea of my meaning.

Permalink Reply by TCLynx on August 16, 2012 at 4:56pm

I don't think I would worry too much about it myself.

Some types of plants do tend to bio-accumulate certain things so if you were constantly catching fish from badly tainted waters and putting them into your system, then it could be possible that the plants could start to accumulate nasty stuff.

However, I got the impression that this was a one time catch fish and put them in the system and in that case the contamination should be minimal and probably far better than eating veggies that are constantly sprayed with chemicals.

Permalink Reply by JRComito on August 18, 2012 at 12:04pm

I hear that. Thanks again for the ease of mind. I called and left a message at Florida Fish Farms, but haven't heard back yet. My order would be so small, probably 50 or so young bluegill to start off clean. I may have to take a road trip.

Yesterday I did my first water quality test since I started the pond in April with Mollies and about 4 hand-sized bluegill, and the results are: ph-7, ammonia-1ppm, nitrite-.25ppm, nitrate-3ppm Just thought I might run those by you and see what you think about it. I have done nothing but feed the fish. I had the tower in the pond directly pumping to the top and dripping through a foam-like media called sure to grow. That did not work so well, it gathered bio junk and algae at the top slowing the trickle, etc. So I am going to go back to Aeroponics for that. I would still like to put a couple of smaller towers into the system, I just need to find a better vertical media.

Permalink Reply by TCLynx on August 18, 2012 at 2:15pm

Zipgrow towers and their matrix media is the only media I can recommend for towers that also provides enough filtration for an aquaponics system on it's own.

Ammonia 1 is not so good, you need more filtration. Ideally you want both ammonia and nitrite to be 0 or as close to it as possible and the nitrate could be anywhere from 0-off the chart and still be ok, I like my nitrate to be in the orange just so I can actually tell what it is.

I don't think Florida Fish Farms will have bluegill till later in the fall. I'll probably be getting a big order of them when I get them. I can probably do another group order with them this fall and sell some to others who want small quantities.

I'm hoping to go get some channel catfish next week. But I only really recommend them for a 300 gallon or larger tank

Permalink Reply by JRComito on August 19, 2012 at 10:35am

The matrix media. I saw that on Nate's page in his photos. It looks like it is rectangular and comes in rolls? I build ponds for a living, and I have not seen that stuff yet. I have found something called Matala, which is a great product for pond filtration in the skimmer or in the waterfall weir. It was developed for Koi tanks and comes in rolls that can be cut to size for the bottoms of those blue tanks. I called them to get some tech info, and I found that it might be difficult to retro-fit it into a tower. I like the idea of the media in the tower being the filter. Before I get my new fish, I am going to thoroughly clean out my FT. It has a layer of pea gravel in the bottom and up on the shelves of the insert that is full of waste, which probably accounts for the high ammonia.

My original thought concerning filtration was that the perlite in the beds and the gravel in the pond would be sufficient, but after looking around here , I see that most folks suggest a sump or an inline bucket filter of some sort. I am trying to keep the power usage down, so I need to figure out a way to include the filter somewhere in the system at gravity or have it in the FT, or something...I have considered making a homemade under gravel filter with some perforated pipe laid in a coil. It would pull most of the poo through the gravel, I guess. Should I maybe remove the bed of gravel? I was thinking of the pond as a big FT so I figured it needed a bed of gravel. What do you think?

I really want to get an IBC tote, and split it 2/3 tank-1/3 bed with gravel, etc., but the timing is not right for the investment right now. So I have and want to make this system work and get to know the in's and out's before I expand. All components other than the storage bins, fittings, and pump are recycled. Eventually, I would like to introduce solar and take it completely off grid. I already top of with rainwater, so we're working toward that end. Some day...:)

Permalink Reply by TCLynx on August 19, 2012 at 5:20pm

The gravel should be in a gravel bed for the plants to grow in. It is rarely good to have gravel in an aquaponic fish tank.

I like to have lots of gravel bed. Keep in mind that the IBC system where you have only the top bit of the IBC as a gravel bed is only enough to grow a small number of fish (like 12) in the tank.

I usually aim for equal gravel volume to fish tank volume for a simple system (pump up to gravel beds and drain back down to fish tank.)

As to the media, Nate worked hard on the development of that media to work right in his towers to hold the plants while also filtering the water while not clogging at the same time. I don't know that any other media would work quite right for his towers.

Permalink Reply by JRComito on August 19, 2012 at 7:28pm

Wow! He made it? Cool. It looks so simple to plant in those towers. He did a great job! I may invest some day.

I am pulling the gravel tomorrow. Thanks. What do you think about the perlite bins? I have read some that the perlite may affect the fishes gills. For argument's sake, I rinse all of the perlite before it goes in so I can get rid of most of the dust which builds up in places you don't want it to.

I like the way you can just move it around and place seedlings or even for direct sowing. We use it mainly for propagation, but I am looking forward to the "squash test". I recently have Sweet dumplings and Acorn seedlings that I am going to try and leave in the constant flow tank for a bit, just to see how they come up. Then I may transplant to our organic veggie garden(dirt).