Building up the food chain in a natural fish farm

Hi all

I have a fish farm that was run like a commercial trout farm in the past, as far as I know, successfully. This means high stocking density, pellets, and all that goes with that. Having bought it as a part of a bigger property, and not done anything with it for a year, I would now like to put it back into use, but in a way that relies on natural sources of food for fish. That means I need to create conditions to develop a highly productive natural aquatic food chain, starting with the lowest trophic level (microorganisms), and all the way to trout and/or other fish.

Water quality is not too bad as the river is as short local one, fed by local streams and they arise in forests that we can see. There are some broad leaf forests (beech and oak, some ash and chestnut) and some are industrial pine forests, grown as crops. There are also some fields, but mostly used for pasture, or fodder production. As far as I know there are no pesticides applied. Local farmers apply some chalk, as the land and water are slightly acidic but nothing more drastic than that - unless things are going on that I am unaware of, which is not impossible.
Some fish farm ponds are concreted, and some are earth. They are about a meter deep, and they run in two parallel chains of pools. One chain contains pools about 6 meters wide, and the other is narrower - only about 2 meters. They run North/South, roughly. All together I think they are about 200 meters long all together, with sluice gates and aeration pipes set up between them.

So - where to start? My thoughts are like this: first clear all canals off silt. Then analyse the infrastructure to see if any amendments or reparations are necessary. Create planting banks. Identify plants to encourage development of different organisms in different pools: algae, Daphnia, Gammarus, Minnows (or other small fish), etc. Then, introduce those organisms that are not there naturally, but taking care not to introduce any invasive species either of plants or animals. Leave them to grow for a year, and monitor constantly to see what does well and what needs more help.

Year two introduce some trout into the trout pool. It will be receiving water from pools containing other organisms, therefore some of those other organisms will have been carried downstream to the trout pools, and they will represent live feed for trout. Trout will grow happily forever after, and when the time comes, end up on our table, or a table in one of the nearby restaurants, or perhaps back in the river to fend for themselves (through the river repopulation programs)

Has anyone got experience on similar projects that they are willing to share? Or has anyone heard of a similar project? I am based in the South of France..

I welcome any ideas, thoughts, questions, new angles from which to look at things etc.

Thank you in advance

Yves

Sounds like you have a nice place there.

Do you have any pictures?

I have professional experience in managing a koi breeding/retail operation held at what amounts to be a managed overpopulation, and during my tenure there managed to eliminate water changes and incorporate plants into the ecosystem. So here's my advice:

One can get started a bit faster than one thinks, especially if you have a bit of anaerobic sludge/gick hanging around the tanks somewhere. If you have cleaned out your ponds thoroughly, add a bit of any one of the commercial nitrifying bacteria inoculants, and either a couple goldfish/minnows or a bit of white non-sudsy ammonia (trust me). Make sure your water is moving through something with a high surface area, we used plastic spirally looking things but gravel etc. would serve the same purpose. The theory is that fish poop ammonia, and 1 PPM of ammonia can kill. The first set of bacteria go from ammonia to nitrite, which is similarly toxic. The next step is to nitrate, which can build up 100 or more times as high before it is directly lethal. The daphnia and such will come from adding pond plants, it would actually be hard to prevent. Make sure your water has a decent amount of calcium and magnesium for PH buffering, I learned about this the hard way because my source water had zero and I learned to manually add it either using crushed oyster shells in the long term, or calcium chloride/magnesium sulfate as an instant fix; the biological cycle will produce carbonates and bicarbonates from these. Basically fish want mineral water not distilled. Stock slowly, a maximum of an inch of fish per square foot of surface area (about 23 cm per square meter) to start with, although you can way more than double this with time. Test your water PH, ammonia, and alkalinity (in pond chemistry, often incorrectly referred to as carbonate hardness, a chemical oxymoron) You don't have to do this, but it certainly helps to get things started on the right track. If you do feed your fish outside food at first, only feed a tiny bit once or twice a week, then cut back; that is, unless you are using catfish like pigs which would be a great idea... And remember that the commercial fish farm folks tend not to practice real chemistry, so if you do your own proper research, and use logic and good common sense, you are already way, way ahead of the crowd.

Hi Cris
Here is a link to the flickr photostream... There are some photos and comments under them to help understand how it all hang together... Enjoy and I look forward to your comments


http://www.flickr.com/photos/91216892@N07/?deleted=8283457415

Have fun

Yves

Hi Bob,

What you do sounds very interesting and I would love to know more. Did you manage to create conditions for koi to freely reproduce? What plants did you introduce and with what effect?

I have a lake full of anaerobic mud, so not a problem. But, I didn't understand what I should do with it... Add bacteria to it? There probably are bacteria in it... But say, I obtain commercially available ones, which are nitrifying ones. Are the bacteria for the net step going to be available naturally, or do they need to be added as well? At the same time? Or not? And then cover it with gravel? How can I check what is happening - i.e. that all the processes that I want are happening and none that I don't want?

All this I should do in the first pond which is the most upstream one. But the point of the whole nitrite/nitrate exercise is to create the nitrogen that is available to plants in the form that they can take it? PLease correct me if I misunderstand. Then, in the following pond downstream I should place some plants, and check that Daphnia are quite happy in there. I have quite a lot of irises in the lake, so will transfer some of them to fish farm to feed creatures. Any other suggestions for plants that are not too invasive but are favourites of other water creatures?

To add the carbonates, I thought of adding the limestone gravel and rocks - the water over here is slightly acidic, so would add them to improve the ph but also to provide shelter for creatures. How much to add would depend on price, I'm afraid. The local stone is granite, and so limestone would need to be brought in from maybe 20 miles or so distance...

What is a decent amount of calcium and magnesium - do you know?

Can you recommend a decent but not too expensive spectrometre for taking all the necessary measurements (minerals, amoia etc )?


Thanks a lot for all your thoughts...

Have fun

Yves

Yeah, the soil here is granitic as well, so I basically had the same water conditions as you. The anaerobic mud would be a natural substitute for buying inoculant, a natural lake has all the bacteria you need. In other words, throw a handful of mud in the top pond and let it cycle through. The way one would tell if the nitrogen cycle is working is to have ammonia and nitrite levels right at zero with a fish load/ one can add plain non-sudsy ammonia to jumpstart or test the cycle as well. I always aimed for a minimum alkalinity of 150 ppm calcium carbonate equivalent, a little more than half as calcium and the rest as magnesium. The way I did it was get a little under an ounce weight of anhydrous calcium chloride and an ounce point two magnesium sulfate heptahydrate per 100 gallons, being sure to pre-dissolve the calcium if you have any fish ( it gets hot, and looks like pelletized food) to cheat and add alkalinity. It cycles through after a few days and raises your alkalinity. The oyster shells should be done as well, I used 20-30 lbs pfor a 600 gallon breeding tank with a heavy fish load, due to the fact that the nitrogen cycle reduces alkalinity over time. The oyster shells take forever to kick in though. If your alkalinity is up above 100 ppm caco3 equiv your PH will be rock steady at 7.4 and very resistant to change. If you want to get the best testing stuff while spending the least amount of money, get a glass probe PH pen, an EC meter, and buy the ammonia and alkalinity liquid indicator tests separate from the kits. You might also get a phosphate indicator too, though you would be able to tell if it got high (more than one ppm means your water looks like green sludge). Just remember to step up the fish load/feed load gradually and monitor the ammonia and PH while doing so, at least in a young pond. Watch out for PH crash until your alkalinity gets up, it would go from 7.5 to 5 flat overnight for me, and the fish would look all freaked out. Actually, you could tell if you had a low alkalinity by testing the PH in the middle of the day and the middle of the night, and comparing. During the day, all the oxygen the algae release forms bicarbonate ions and tends to raise the PH, whereas at night they all are breathing out CO2 and thus forming carbonic acid and lowering the PH. With plenty of alkalinity the PH won't change much, with none it will fluctuate, and if you have more sodium than calcium, then it will fluctuate wildly. My koi bred freely as long as their babies had somewhere to hide, otherwise the population shall we say remained stable. Also I would be careful importing food fish breeding stock into a good pond, I trust natural pond water but these fish are like buying a feedlot cow and rehabilitating. I recommend a potassium permangate dip or at least a strong saltwater dip. The fish don't like it, but I'm sure they like it much much more than costia parasites.

Yves Ball wrote:Hi Cris
Here is a link to the flickr photostream... There are some photos and comments under them to help understand how it all hang together... Enjoy and I look forward to your comments


http://www.flickr.com/photos/91216892@N07/?deleted=8283457415

Have fun

Yves

Beautiful. We have a fish farm near me, but it is very "commercial" with rectangular concrete ponds ,railings etc. I was imagining something like
that, but this looks really natural.

That landscape looks a lot like the region of the USA where I live.

Yes, there is some concrete on the bottom and sides of some pools, but all pools have at least one long side that is not concreted, and some are completely earth. It is a bit overgrown, so there are places that one cannot get to without going though a lot of thorns, but mostly, it is accessible and in need of tlc...
Glad you like it... I hope in the future it gets even better...
Y