Ravnis

Overwintering tilapia with minimal heating

8 posts in this topic

It's been a four year project, but preliminary results are encouraging.  I have steadily  been letting the water temperature get lower each winter and spent a lot of money on utilities to keep the tilapia warm enough to get through the winter.   The last few months have been colder than normal and with minimal sunshine the last 3 weeks the water temperature has been hard to keep up.  Water temperatures have been 46F to 52F for the last month with 46-48F this last two weeks. Solar water heating and a forced air heater set at 50F have been the only source of heat other than a single 300 watt heater in a 4000 gallon tank.

 

The water temperature has climbed since last wendsday and the fish are biting my fingers as I check the water temperature now that it's 56F.  It peaked at 60F and I threw a little food to them and they ate it within seconds. I don't want to overload the biofilter that is sure to be weakened by the cold as well.  I will feed minimally and monitor for ammonia buildup.   I did loose 4 fish during this, but do not see any signs of having lost more.  I know the cold weather has wreaked havoc on fellow ap'ers, but wanted to let you know there is hope to reducing utility bills and overwintering fish.  I doubt howerver that they would have had time to acclimate in a smaller volume system. Temperature changes occur over days due to the system volume close to 5000 gallons. 

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Ravnis,

It has indeed been brutal this winter for a lot of us in this country. Glad to see your're adapting. I'm still considering a trombe wall on the south end of a pole building for the building that will house my cool and cold water tanks.

I would love to do some aquaponics with this in the winter with an add on greenhouse but don't like their heat loss at night or on cloudy days.

Edited by Cecil (see edit history)

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Glad to see your results.  When I was doing my water exchange the other day, I realized that water temps were not my only problem.  Like you observed, the cold had overloaded my biofilter.  I had cut off the grow beds to minimize heat loss, and I knew that cold weather affected bacteria, but somehow I didn't make the complete connection.  As things turned out, a handful of my tilapia survived by hiding very close to the heaters.  They are feeble and still might not make it, but I'm giving them all the attention I can.  Fortunately the days have been warmer and the greenhouse has been especially warm, so the water temps have gone up nicely in the day which helps the heaters at night.  I can honestly say I've learned a great deal through this gosh awful winter.  I'm ready for spring and hoping for a 'normal' Georgia winter next time.

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I second your sentiments and experiences Sam. The harsh winter has been quite a learning experience, mostly in very high utility bills. My water temp's were at 59F yesterday, and the fish seem fine - eating normally. Although not as a big a system as Ravnis', the room is insulated well and temp's have come down slowly.

 

I'm so ready for the spring, and hope that next winter is less extreme.

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Making temp's move slowly is a key as well as stopping feeding when anticipating a cold front so the load on the biofilter drops.   

 

Sam, Don't give up hope.  The first year I tried overwintering tilapia  I started having fish mortalities at 57F   and after several generations later they are handling much colder temps.  I think the ones that survived to breed had more cold tolerance.    I think we're all hoping that the major freezes are over for this year.  

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The topic of solar water heater has arisen again.  This site is a treasure trove of ideas.

 

<a data-ipb="nomediaparse" data-cke-saved-href="http://www.builditsolar.com/Experimental/PEXCollector/Construction.htm" href="http://www.builditsolar.com/Experimental/PEXCollector/Construction.htm'>http://www.builditsolar.com/Experimental/PEXCollector/Construction.htm" "="">http://www.builditsolar.com/Experimental/PEXCollector/Construction.htm'>http://www.builditsolar.com/Experimental/PEXCollector/Construction.htm'

 

The solar heater I used in this thread was a 16 foot long version. I got around 4C or 8F degree rise with it.   I used 1/2" pex, but it constricted flow , so if I was to do it again I would consider 3/4" instead.

Edited by Ravnis (see edit history)

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I am not 100% sure of what tilapia we have.  I think it is a blue.  We pulled it out of a really cold stream when it was not even an inch. Cold like refrigerator water.  It is now in room temp and doing just as well.  If our fish is a native and a blue then I question rather they  ( the blues ) need any heat at all.  If it is an escapee from a fish farm it had a long swim to get where we found it. Maybe they mate better in warm water? This one had to be hatched in the late winter.  Even colder water then.  We can buy them full grown at the fish market, alive and ready to eat. That means people do farm them here, somewhere. And also there is a market for them if needed. Regardless I think cold water fish tastes better. I would purge them in very clean cold water, no food for a few days before culling. At the end of the time drop it down so cold that they go to sleep, then enjoy the fish.

 

Maybe if you have cold temp problems, switch to blues. Then the problem should be switching over the bio load back to a filter if the GBs are turned off.  If I had an extra fridge, I would stick him in there and see what different temps do.  I only have fish die here if the water gets too warm. The cold the water the more O2 it can hold.

Edited by Deuem (see edit history)

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