Howdy y’all, I apologize I am not here as a horse owner, although I do love horses just have never had the land or $ to be able to own 1.
The reason I am here though is, I’m from Kansas & we own fish & have quite a few different sized tanks. Unfortunately our largest tank is only a 55gl tank & I currently have 2 beautiful Oscars that have extremely outgrown that tank… With the 2 of them in there we basically have no other room for our dozen or so other cichlids from a very large blood parrot to 3 very beautiful & quite large Jack Dempsey’s.
My father has a beautiful backyard that he has built along with a big waterfall & a pond that’s probably between 250-500 gal easily, (just a guesstimate). He says it’s okay I can put them in it which I was thrilled about & with it being summer in KS now they should be just fine with as hot as it gets here during summer.
That said, it’s still KS & our winters here get pretty harsh & Oscars tend to grow to their environment (which these 2 don’t all they seem to do is grow lol) so I am certain that they won’t fit back in our 55gl after summer ends. My father’s friend has a koi pond that he has fish in year round & he says he uses a livestock heater & they live just fine in the winter… So I’m curious about y’all’s recommendations on best heaters for livestock tanks. It’s been our experience with tank heaters at least that it’s hard to find a reliable submergible tank heater that will last for any length of time. Is it the same way with livestock water heaters & if so do y’all have any good recommendations on what you think is the best brand based on reliability & durability?
Thanks for any help you can offer me regarding this topic as we love our fish like they are family so we actually care about their well-being like we would another human so it’s important we get the best items to keep them safe & most importantly alive. Lol. Oh & I hope you don’t think all the y’all’s are me being condescending I swear that’s just the way I talk honest to God. 
Thanks again in advance for any recommendations you can offer. God bless.
Oscars are tropical fish and need a temperature of about 75-80.
A stock tank deicer won’t heat to that temperature. They heat just enough to keep water from freezing. Keeping an outdoor pond at tropical temps over the winter isn’t realistic, and will be really quite costly.
Even in the summer, it’s likely that an unheated outdoor pond will be too cold for them, and they’ll die. Oscars and Koi have very different requirements and are very different fish.
If you don’t have space to house them in an aquarium, it would be best to re-home them. Your local fish store or aquarium hobbiest groups could help.
We used them to keep a water hole open in the koi pond, to prevent toxic gas build up (along with aerators and keeping the waterfall running year round). But no way would it actually heat the water. Koi are fancy carp, they’re designed to live through the seasons.
Welcome to COTH! I love Oscars and would love to see pictures and hear more about your fish. They have such personalities.
I agree with Simkie that it’d be very difficult for you to keep the water to the temperature they need to thrive. You would also run the risk of losing them. They’re very gregarious and curious as you know - which makes them easy prey items for herons, fishers, bobcats and other predators.
I feel your pain trying to figure out the best set up for your fish. I have a 11 year old plecco that just got an upgrade to a bigger tank.
Is it possible you can find a 75 or 150g tank? They’re huge and take up a lot of real estate - and I would have some concerns about the water weight on the second floor of a house — but I think that would be a better solution for you financially (and including safety) than putting them outside and risking them freezing or being eaten.
Koi are Carp, and as such, can survive in a mud puddle. You need to provide a tropical environment for your Oscars, and I doubt you will be able to accomplish this outdoors, at least not given anything like a budget.
Your best bet will be to watch your local Craigslist and other classifieds, to see if you can’t score a large Acrylic tank like those used in a Tropical Fish store. Brace yourself for the bill, but I see no other reasonable option beyond ridding yourself of the obnoxious critters.
(We have kept Oscars in the past, with experience similar to what you describe. I stand behind my “Obnoxious” rating.) :-D.
We have a koi pond deicer for our koi pond. It’s basically the same as a stock tank heater, but made for that purpose. Plus, I think (assume) it keeps the water colder than an actual tank deicer. In cold weather, there is a ring of unfrozen water around the heater, but everything else freezes over.
Not really Oscar habitat.
Hi Tidbit
Reading thru, I realize nobody has answered your questions, so here is a brief take.
There are two kinds of stock tanks, steel, and plastic/rubber. Steel tanks are galvanized, but they still rust eventually, and between the iron oxide, and the zinc, I don’t know how suitable they would be for fish long-term.
The rubber tanks, and the Rubbermaid ones in particular (since that’s what we have), are durable, and with the more or less standard “Farm Innovators” heater installed, they will keep a 100 gallon tank relatively ice-free in single-digit-negative (°F) temperatures, and keep liquid water available at least down to -25, but ice will form around the edges. In general, those heaters try to maintain a water temperature of around 40°F via an internal thermostat, and draw 1500 Watts per the packaging. We typically get 3-4 seasons from one before they quit, and I keep a spare or two in the barn.
One of these could undoubtedly support cold water fish, and you could probably find or build a heater/control system that would keep the water at 70-80 degrees. You can use foam board to insulate the tank, and even float some foam on top to reduce heat loss. You might even get creative and put the pump/filter/heater indoors, with foam insulation on the supply/return lines, and a strong flow to maintain tank temperatures, but your electric bill in cold weather is still gonna take a beating. So not impossible, but spendy.
Hope this helps.
(Edit) For a start on heating/temperature control technology, and a source for high quality components, try Omega Engineering.
https://www.omega.com/en-us/search/?text=tank+heater
I kept “feeder” goldfish in a 65gal galvanized tank for over 10yrs. It never rusted & they grew to nearly a foot long.
Tank lived outside, on my back patio & a floating de-icer kept it open & aereated over Winter.
Sadly, when I was gifted a new 165gal galvanized tank to give these goldtrout more room, something leached from the new tank & all 5 died in a week.
I replaced with more 25¢ feeders, but after 5yrs & more growth - largest took 2 hands to lift! - the de-icer failed last Winter & tank froze nearly solid.
Amazingly a single fish survived - smallest one, actually born in the tank - now 6" long.
I just bought 4 more teeny feeders & so far “Lucky” seems to be following the “Fish are friends, not food” thinking 
OP:
My brother had Oscars & they seemed very personable as pets.
Maybe consider keeping yours indoors over Winter & moving to your Dad’s pond when it gets warm enough?
I did this for years with the goldfish.
Until they were crowded in a 20gal aquarium. Then they went outside year-round.
But, as others pointed out, they’re carp.
“Lucky” :-D.
Years ago, we had a pair of Ducks. Don’t ask me why, but they were, at least, an amusing crew. (Unlike the Geese; don’t even get me started on domestic Geese.) Anyway, lacking a pond, we got a kiddie wading pool that we would fill, and let them play in it. One day, I brought home a dozen feeder goldfish and tossed them into the ducks pool. The Ducks went wild. Once the carnage was over, I found one lonely fish, gasping in the grass by the pool. I took it in the house and put it in a small aquarium. We named (by now him) “Lucky”. Lucky grew into a handsome orange and white “Koi”, quickly outgrowing the 10 gallons of real estate. We gave him to some friends for their real-life pond, were he thrived, and lived happily ever after. Or at least he was still there mooching treats the last time I visited, several years ago.
Carp are vegetarians, aren’t they? Or more like opportunistic feeders; nominally vegan, but not above an occasional fillet if the opportunity presents.
(Edit) And they live forever IIRC.
I appreciate all the answers from everyone & yes I realize the difference between the types of fish that Oscars are compared to Koi… However I know that it gets mighty hot here in the summer high 90’s & 100’s are not at all uncommon for us so that’s why I was hoping to get them through the summer in the pond with a heater until I can save up enough for a large custom built tank. & To you 2dogsfarm, that’s hilarious about the fish surviving over winter in a frozen tank as my dad at their previous house had a waterfall pond setup that he put some little gold fish in & that same exact thing happened & a few of his also survived being frozen solid or at least had enough oxygen in the little bit of water that wasn’t frozen for them to survive over winter lol. Who knows maybe that Walt Disney guy was onto something with being cryogenically frozen lol. As for the pond it’s a cemented in pond/water fall my dad is a big dyi landscaping type of a guy, 1 of those dudes who refuses to sit back & enjoy life cuz they’re afraid if they stop working they’ll die… Lol so he basically just works if he’s awake which is very often as he’s a 5am type of morning person & pull out the hallogen spot lights when the sun goes down & work till 11-11:30pm type of dude so yeah he always has the most incredible landscaped yard in the cul-de-sac no matter where he lives. But his pond is like at least a 1,000 to 1,500 gallons it’s quite enormous & he has a big ass 500gal water tank up above (cuz this is in his back yard which is a sunken backyard so that the basement doors slide open & your in the backyard) which he uses to store fresh rain water that he gets when it rains cuz his back yard is built so that it drains all into 1 section where he pumps it up to the water tank & it’s then filtered so that he doesn’t have to use water from like a faucet or something since 1,000+ gallons would be a fairly hefty water bill once you consider the evaporation how often you would have to add water. We had a REALLY dry year a couple years ago & he did have to add water from a house faucet & a hose & he said just adding a hundred or so gallons every few weeks he noticed a big difference in his water bill so I couldn’t imagine filling it up with water that way.
Anyways my main goal is to get my Oscars through the summer in his pond hopefully so I can save up enough for a custom like 250-500 gal tank before winter gets here… I know that’ll set me back a couple grand if not more but I make good money but not good enough that I don’t even have to save up for a purchase of that size lol. If I have to put a few heaters in there & pay an extra $100-$150 a month in an electric bill so be it, I’ve been a fish hobbiest for nearly a decade so I know it’s not at all a cheap hobby. But we love our Oscars or at least I do my wife prefers her cichlids (Jack Dempsey’s, Convicts, blood parrots etc.) I know Oscars are also a type of a cichlid she just doesn’t like em cuz once they get as big as mine they’ll eat whatever they can fit in their mouths lol which I think is awesome she doesn’t think that quite as much as I do lol. Especially if 1 of her cichlids gets eaten & as big as these Oscars are getting it might not be long before it happens.
Anyways thanks for all the replies everyone I’ve got some decisions to make before I give it a shot plus I probably won’t make the move for another month so it’s full on 95°+ summer heat in affect before trying to teach these Oscars to survive in slightly cooler temp then they’re used to lol. Wish us luck.
What will you do to prevent predation, if you put them outside? You may want to get a heron or owl statue.
I think your mind is made up OP, and I wish you the best of luck! Just don’t forget that being out in the wilderness exposes them to all kinds of opportunists looking for a hot meal. It may be my own experiences showing, but I haven’t known anyone to have luck with keeping their fish outside - and I’ve plenty of friends who thought it would be fun to add a koi pond to their back yard, only to have birds visit for sushi dates.
