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SamBurton

Overwintering Fish In Outdoor Systems

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I'm trying to overcome some of my limitations by trying to overwinter fish in one of my outdoor systems because I want to grow out some bluegill and catfish. Here's my thinking. When I shut down my growbeds in late fall, I will essentially have a RAS. I will continue to circulate the water through my filters, and keep plenty of oxygen in the water. I'm thinking that should keep the pipes and pump from freezing.  Do hobby koi enthusiasts keep their filters running all winter?  What happens to ammonia in the cold when nitrification stops?  I'm guessing that each spring my system will be just like starting over, but because the fish are bigger, there will be more stress on the biofilter to kick into gear. Is there any benefit in adding live bacteria at that time?  I am looking at one or two of my 250 gal. IBC totes for the experiment.

 

Thoughts?

 

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Hi Sam

Around here koi/goldfish keepers usualy shut down the filters and blend off & drain piping to avoid any frost damage.

Keeping the water sirculating can cause supercooling to the FT and if there is a blackout (more common in winter storms) there is a risk of frost damage.

wery common to instal insulation/lid and maybe a small ice-free device to keep a hole in potential icecap like this :

http://www.oase-livingwater.com/tr_TR/water-garden/products/cleaning-care/ice-preventers.html

 

here some on winterising fish/tank

http://www.happyponds.net/PreparingFish.pdf

 

http://www.raleighlandscape.com/Pond%20Reference%20-%20Overwintering%20Pond%20Fish.htm

 

http://www.canadiankoiandpond.ca/articles/article11.html

 

If fish is fed it's special diet and particularly koi can get problems below 10C do to their simple digestive system.

 

cheers

Edited by ande (see edit history)

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Bluegill will actively feed all winter long. They'll consume less than in the warmer months, mostly maintenance feeding, not mass building. They will still feed aggressively, just much less frequently. I catch a lot of big, healthy bluegill under the ice while fishing lakes and ponds in the winter. Bluegill will still put on some weight in winter, but much less than during the warm months. It is usually worth feeding them, at a reduced rate, in the winter.

Catfish tend to slow their feeding dramatically in the winter and it's usually not worth feeding them much at all during the cold months. See this: http://www.aaes.auburn.edu/comm/pubs/highlightsonline/fall97/catfish.htm

Any feeding program in the winter needs to be based on your greatly reduced biofiltration capabilities during the cold months. In truth, it's better NOT to feed than risk ammonia poisoning, but small amounts of food on those days when you get warmer winter temps is usually worth it, in moderation.

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Channel Cat: http://www.fao.org/fishery/culturedspecies/Ictalurus_punctatus/en   indications are that feed can even be completely withheld for winter months.

 

They don't have specific information about bluegill but University of Illinois has done some testing indicating that bluegill was more susceptible to ammonia levels at colder temps.  Reducing feed to match the capabilities of the biofilter would help prevent problems.  They are a common pond fish here in Illinois and often survive in near freezing temps under a couple of feet of surface ice.

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Channel Cat: indications are that feed can even be completely withheld for winter months.

Agreed with a "but". The Auburn link I provided above agrees with the "no feed during winter" strategy. Basically, in their trial, the CC lost about 10% of their weight when food was withheld over winter, but then quickly regained that lost weight in the warmer months, to the extent they reached a roughly similar harvest weight as the fish that were provided feed during the winter months. However, these ponds are earthen ponds which provide a number of natural forage items for the catfish to dine on through the winter, even if not being fed. In a RAS, natural forage items do not exist, which makes it a bit more challenging when seeking to strike that perfect balance in a winter feeding program.

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Not at all man... You've got it right. :)

I just wanted to add a little clarification, that it can be a little difficult sometimes comparing earthen basin based trials to RAS trials. So many different variables apply depending on what is being tested/trialed. Still, great insights can be found through both. Our Moderator, Cecil Baird, who's a master at raising amazing looking, trophy sized fish in earthen ponds will be the first to tell you that RAS has its own set of unique differences and challenges, and sometimes the assumptions we could take for granted on one side are quite different on the other. It makes it fun. :)

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Another point to consider Sam.  If the goal is to just keep the water above freezing instead of trying to reach a certain temperature for growth,  Cost of heating goes down drastically.  Case in point,  by changing my heater setpoint on my kerosene heater from 60 to 45F,  used dropped from 2 gallon per day to 2 gallon per week diesel.  It was $4 gallon so went from or $54 dollars a week to $8.

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Sam, 

 

if your weather is anything like ours in dallas.. most of he winter it's 40-50 degrees outside and only for a few days at a time does it drop below freezing... and usually only at night...

 

 

SO i basically run my RAS year round, i usually only run aeration in summer. but i also lighten my bio load between bringing some fish indoors(tilapia) and fall harvests. When the cold snaps come through i just turn off the pumps while weather is freezing and turn them back on when it's not... 

 

This year all of my fish tanks were frozen for about 3-4 days with about 2 inches on top. I have gone as long as 2 weeks with frozen tops and lost types of fish in some tanks but others were fine. It seemed to relate mostly to bio load and fish species, but the larger the fish tank the better.  Goldfish did the best.  Sunfish bluegill,redear and LMB did well and  the HSB and catfish were less tolerant.

 

 

As soon as the cold snap is over and outside temps are above freezing (usually sunny days)  i turn the pumps back on and the water from the bottom melts the ice pretty quickly.

 

 

if i was doing RAS in a place where it froze for months at a time, you have a lot mor obstacles trying to keep RAS going year round. i would try to insulate the tanks as best i can, cover it with plastic like a greenhouse and potentially run a stock tank de-icer sparingly (maybe only in the early morning) just to keep the ice melted. 

 

 

-edit- yeah, +1 Ravnis.. there's a huge diff in trying to keep warm temps for tilapia and keeping water from freezing for native fish. Probably millions of BTU's difference

 

 

brian

Edited by bcotton (see edit history)

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Sam, I've been following this closely because in the south we only deal with extreme cold snaps for only several days at a time, blame it on El Nino, whoever that is... I'm planning an outdoor set-up this spring, but not enclosing anything under a greenhouse, though I do plan on locating my stock tanks right beside my house for added protection. I live on the GA/FL border on a barrier island about .5 miles from the beach, so the weather is buffered by the ocean, BUT when an arctic cold front decides to push low the temps can get down into the upper 20's. I plan on installing one of these...

http://www.tractorsupply.com/en/store/allied-precision-2002dp-universal-drain-plug-de-icer

in my sump tank to keep the water above 45F for blue tilapia, but I don't think that I'll set the thermostat for any higher than that to keep them feeding all winter. I talked to a guy that has tilapia about 20 miles inland, where the lows can get 10 degrees colder, and he says that he tried a similar heater one winter and it raised his electric bill by $300/month, not worth it, imo. He says that now, during cold snaps, he trickles water from his well, which is 60F year round, into the system, which keeps it above 45F. I plan on circulating water through fishtanks/sump/biofilter during winter months, but not growbeds, unless I can enclose them in a heated greenhouse. good luck staying warm...

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The heater dont have to keep the water to a certain temp.  the water around the heater will form a warm area.   I had some fish in two tanks, one with a heater and the other without.  The fish in the tank with the heater survived while the others died despite the average temperature being the same.

 

The last time I looked at the tractor supply heaters they had a maximum setpoint of 41F , but that was several years ago.  I was also concerned that certain metals can leach into the water an sicken/kill fish so I didn't want to take the chance.

Edited by Ravnis (see edit history)

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Last winter, my electric bill was roughly the GDP of a small country. It cost me more to try and keep Tilapia comfortable than my chickens, ducks, rabbits and goats combined. That's not a good Return on Investment. By switching to local fish, minnows and goldfish, I will reduce my cost by 70% in winter. My wife doesn't eat fish, anyway. 

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Tilapia probably have the most hype for fast growth, hardiness to all conditions except cold, and cradle to grave operation.   I think they are a little overrated, the only reason I have not converted to catfish or bluegill already is due to discovering my fish are surviving water temps in the high 40's (F)   and seem to be adapting to the temperate climate.   They do still require a transition of several weeks to that temp a sudden drop kills them.  

 

As far as food conversion rates, it seems to me that water quality and feed quality matched to breed metabolism is more critical than species.

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Sam....I would definitely go with cold water fish where you live, have you considered trout? I know for a fact they are delicious :thumbsu:

Ravnis...41F is not going to help much, maybe for people with cold-water fish outdoors, just to keep the tanks from freezing :coldb:

 

There are aquarium heaters out there for big tanks, I'm going to put a link below, but they also come with big prices...

 

http://www.jehmco.com/html/heaters.html

 

I'm going to shoot for a heater that buffers against those sudden drops, but NOT one that maintains tropical conditions year-round, such as an indoor aquarium, because as Sam found out, you pay for every kilowatt hour that you burn.  I would select a cold water species if I thought that I could maintain it during the summer months, but during that time the highs here are 90F plus, I know because I'm out there working in it every day, and its hard on me!

 

Ravnis...you said your fish "seem to be adapting to the temperate climate".  Are you talking about genetic selection, as in over several generations?  Or are you talking about individual fish becoming more and more hardy as they become older?

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Mr Dave, both actually, I'm on  several generations now since I started overwintering the original batch of tilapia in 2009 and are using descendants from them still. They tend to have several generations a year as they start producing between 3 - 6 months of age.  The main thing I like about them ,  no hassle replacements..  

 

The first time I used a propane forced air heater, very expensive.   The second time I used a temperature probe setpoint controller from aquatic eco systems, a pump, and a tankless water  heater.  I had plans for going commercial at that time and started with 20 lbs and by October had 2000 lbs, Got 1700 fish from one female.   The small fish die first to cold, the older fish are more resistant.  I kept the water at 75F and it ran me 300/mo in propane  and any chance of profit went up in smoke literally.  It was my first attempt and caught up in the excitement and dream of making tons of money on fish... and the coldest winter in record for 30 years.  Talk about bad timing :D

 

 

So I started experimenting and running several different overwintering techniques that would not break the bank.   A  true aquaculture setup in an insulated building  is the most efficient , provided you can get enough water for the exchanges.

 

An extremely close second is a greenhouse with solar heating and heating the air just to get you through the night and cloudy days. The amount you spend is determined by how many cold days you have.  I let the water get to 47F and stay there last year with only a few fish moralities due to having catfish  mixed with tilapia. Normally the tilapia are the fastest swimmers and can't be caught, but in cold water there systems slow down before the catfish and they become easy targets.   Best to keep separate if not able to keep them in high 60's.   

 

  Anyway I use radiant floor panel plates painted black on top of 1/2 pex pipe as my solar heater and pump through that.  15F outside and sun shining, it will keep the greenhouse 70F+ and maintain water temperature +- 8F.    A kerosene forced air heater 70k btu keeps the greenhouse temps   up enough to slow the temp drop and Keeping the air 45F - 50 F will slow the water temp drop to several days and give time for the sun to come back out and allow the fish to acclimate a few degrees at a time over a month.  

 

They started dying at 57F the very first cold spell, but they went from 80F to 57F in a matter of 2 days.  I did not have any heat set up yet that first year and had to scramble to design and build one.  Now they handle constant 47F  with brief periods below that.  This setup cost around 10 to 20 gallons of diesel with the mild winters we have been having, double that on an extremely cold month.

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I've thought about trout, but have heard I need raceways rather than my simple recirculating IBC and cattle trough systems.  I'm going to get a few bluegill this year for sure, but my focus will be minnows and goldfish.  I'm itching to try yellow perch, but only need a few and it looks to me like I would need to buy more than I'm ready for. 

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Hey Sam,

 

I visited someone in Vermont that kept trout in circular tanks and had air pumping into 4" pvc set in a 'S' (two 90's facing opposite directions) and this created a strong swirl. I've considered trout because they are native and quite delicious, but I've been concerned that they are not as tolerant of water quality issues and keeping the water cool enough in the summer would be quite difficult. Had I gone with trout, I'm sure that I would have mass killed the lot with some of my learning curve mistakes.

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Have you considered something besides fish? Or do  you really want to grow fish?

 

  Vermiponics might be more in line with your other endeavors. Worse comes to worse, you feed the worms to the chickens and ducks and use some to catch some bluegill and catfish.   A pound of worms should bring in much more than pound  of fish and should be much easier to overwinter.

 

Another option might be worth considering is prawns.  Grow out season 4-6 months depending on age group purchased. Still trouble with winter, but a spring/fall crop is doable. 

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Ravnis,

 

Prawns are right up my alley.  Fast grow out is what I really like, plus I love shrimp, albeit the salty variety.  The thing is I always thought you needed to set up somewhat elaborate netting because they fight.  Have you ever tried?

 

Edit: I might move this over to its own thread...

Edited by craig1267 (see edit history)

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I like fish. I just need to find the right varieties for my situation. I do raise worms. Besides two small worm bins, I have started putting them in my wicking beds and have a feeding station on one end of the bed. Vermiponics, though, just doesn't interest me. Frankly, I'm loving DWC hydro more and more and am expanding that. I had some success with a hydro flood and drain table last year, too. I'm going to try a bit more of that, as well. Still, the goldfish work great for me, but I want some edible fish as well. We'll see how the Bluegill do in a system this year. I have high hopes.

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