trying to start out

[Jarid Bowers]

I am in Missouri and just trying to learn alot before I start out. I know I want to do an aquaponics system inside a greenhouse. I was originally thinking on raising catfish but they dont reproduce in tight spaces well.  I was also considering Talipia but they require warm waters and here the winters get cold. I am trying to get my greenhouse to be more or less self sufficient and I do not want to pay alot in heating costs. What energy efficient ways can I heat the water without alot of money?

[TCLynx]

I expect that in Missouri finding a fish farm to get channel catfish fingerling should be pretty easy, channel catfish will grow faster and bigger than tilapia anywhere you are not keeping your water quite warm.  Even here in central FL, My catfish grew much faster than the tilapia (In my two years of keeping tilapia I only ever got one of them up to 2 lb and most of them only got between 8-12 oz in a single season grow out.)  My catfish (granted purchased as fingerlings rather than fry) generally got to between 1 1/2-3 lb in a single season grow out and the one I kept for two years got to 10 lb.

 

If you need a fish that can handle smaller tanks and cooler water but might still breed for you, think about bluegill.  They might not get big but they are good eating.

 

energy efficient ways to heat water, uh, if you are already running your own steam generator or boiler or something perhaps you could heat some water with the waste heat but when you will need heat the most things like solar heating are going to be your least reliable.  You need a huge amount of thermal mass or storage water to really make good use of solar water heating for aquaponics.

[Jarid Bowers]

Well will catfish reproduce easily like talapia? I do not want to have to keep buying fingerlings.... kinda a self sufficient biosphere thing.

[TCLynx]

Catfish do not reproduce as easily as tilapia.  Generally Channel Catfish need to be between 3-5 years old to reach reproductive maturity and most breeding of catfish takes place in ponds.  I suppose it might be possible to breed them in large tanks but making sure you get male and female catfish in the same tank is more challenging than with tilapia.

 

Channel Catfish breeding, the male will seek out a cave (they often submerge milk urns in ponds for captive breeding of channel catfish.)  And then entice a female to lay her eggs there and then the male will fertilize them and remain in the cave fanning his tail over the eggs to keep them well aerated till they hatch.  In captive breeding the handlers will go out and check the urns for egg masses and collect them to bring to the hatchery where they clean them and place them in shallow troughs with agitators that act like the male Catfish's tail over the eggs until they hatch.

 

I one had some one tell me you could use a cubic meter tank to breed channel catfish but I don't know if they ever actually managed it.

 

If you really need to breed your own and don't have a larger pond.  Then Tilapia are easiest if you can keep water really warm.  But, I know people who have had bluegill breed for them in swimming pool systems.  Bluegill are another fish that is known to over populate so I expect breeding them can't be too hard.

[Jarid Bowers]

hmmm so scratch catfish and look at bluegill and talpia. How do most people keep the talapia water warm? And where would I buy bluegill?

[TCLynx]

Check to see if there are any fish farms that provide fish like catfish, bluegill or bass for stocking farm ponds, they will probably be able to sell you bluegill.  You might also check with feed stores to see if any of them know of fish farms that do pond stocking in your area.

 

Tank heaters for keeping tilapia water warm.  During some months you might get by with solar heating of the water in black HDPE pipe but that might not be enough during winter.  I know of some systems where they insulated and then put hydronic heating tubing under the liner of fish tanks, raft beds and even gravel beds to pump water heated by a boiler through.  All depends on how cold your growing space gets and how warm you need to keep the water.  If it's ok to let the fish slow down for winter and not grow much plants through winter, letting the water drop to 60 F will save money on heating but tilapia don't usually eat or grow much once the water gets below 70 F.  With the bluegill you can probably let the water get much cooler and just keep it warmed enough so you won't be at risk of anything freezing in the greenhouse in winter. 

I suppose it all depends on how much you expect to keep growing through winter.  Winter here is my best growing season so I'm happy that my catfish keep eating in water around 60 F though they are eating less, I'm still getting some nutrients for my broccoli and greens.

[Jonathan Farrand]

Check out you tube. I have seen alot of different ways of heating greenhouses. Rocket mass stoves with a buried pipe seems interesting. And I guess rocket mass stoves consume less fuel because of their design. I live in a cold climate too and am just using gold fish for now. Our plans are to run greenhouses similar to what was mentioned. I too will have to work out the specifics.

[Cori MacNaughton]

Another thing you might try is digging down below the frost line for your fish tanks, thus tapping into the thermal energy of the earth, which will act both as a buffer for your tanks and lessen or even eliminate the need for additional heating, depending upon the type of fish you ultimately choose. 

I'm not sure of the ground temperature in Missouri, but I know in much of the temperate U.S. it is around 55 degrees F, which means that even for a warm water species like tilapia, they would survive even a complete failure of the heater,  although they would go dormant until the temperatures warmed up substantially.  It would also help a cold water species such as trout to survive even in very hot summers. 

I am planning on doing this in my large system in Tennessee as an aid to getting off the grid as soon as possible.




Jonathan Farrand said:

Check out you tube. I have seen alot of different ways of heating greenhouses. Rocket mass stoves with a buried pipe seems interesting. And I guess rocket mass stoves consume less fuel because of their design. I live in a cold climate too and am just using gold fish for now. Our plans are to run greenhouses similar to what was mentioned. I too will have to work out the specifics.

[TCLynx]

Just keep in mind a few things.

 

1-In Flood and drain aquaponics, the media beds make a really effective air to water heat exchanger.  So, even if the ground temp down below the frost line might be an average of 55 F, that doesn't mean that simply having the bottom half of the fish tank coupled with the earth is going to keep your water from getting below 55 F on cold winter nights if you are flooding and draining gravel on those cold nights.  (My big system for the first two winters had an in ground fish tank, in Florida where the average ground temperature is about 72 F, and I still had to run warm water from the water heater into the system on a few freeze nights per winter to keep from killing the tilapia.  That was even with me shutting off the flow to the grow beds overnight.)

 

2-in a more temperate climate, if you are doing the geo coupling with the fish tank with an average ground temperature around 55 F, this may make growing really warm water fish difficult since the ground temperatures are going to tend to keep your water cool during the warm season and they won't help warm your water enough during the cool season to actually grow the fish.

 

Now I think digging the fish tank in and growing cool water fish may be a really good option for many people.  The earth will help keep the water warm enough so that hopefully only minimal extra energy (perhaps heating the air in a greenhouse in winter) would be needed to keep the water from freezing and having the earth help keep the water cooler in summer might make year round trout possible in the right climate.  Opening up the greenhouse in summer to keep it from getting too warm of course.

[Jarid Bowers]

I appreciate all this info.Thank you