Need Heater for Oscar Fish?

Topic: I was wondering if I need a heater for my Oscar tank? I heard they are tropical fish but my house stays sort of warm all the time. What temperature should the tank stay? Do I need to buy a heater for my aquarium? How do i know what size to buy? I just adopted this oscar fish to care for.


*Awarded Answer
Posted by Megan G: You should have a heater in your tank just in case temperatures drop in your house. You want a tropical temperature between 75-82 degrees Fahrenheit. You will need to figure on 5 watts per gallon roughly to heat your aquarium. Heaters will heat more than that but that’s a rough estimate to figure on. I would advise buying a eheim Jager brand because they are taking over the industry! They use way less electiricty and they heat better and are cheap! Here is an amazon link to eheim jager heater.

EHEIM Jager Aquarium Thermostat Heater 300W
List Price: $34.99
Price: $32.06
You Save: $2.93
Price Disclaimer

You can set it on the lower side to save some electricity because these fish are pretty tough. I’ve seen people keep these fish in ponds that get pretty cold at night and they do just fine. Most people find themselves keeping their oscar tanks on the warm side though because of the other fish they are keeping with the oscars. Do you have other tropical fish that aren’t as tough as them (temperature wise).

EHEIM Jager Aquarium Thermostat Heater 300W
List Price: $34.99
Price: $32.06
You Save: $2.93
Price Disclaimer

Reply from Author: I plan on buying some Silver dollar fish today! It’s funny you mention that. I heard that silver dollars NEED strict temperatures and when it changes too fast they can get sick.. So I will be definitely getting a heater. Thanks for your help!

Posted by Alisha B: I have a situation next month where i am going to have to have my oscar out of my house for about 24 hours as my house will be heated to 140 degress for 8 hours and needs time to cool. Unfortunatly moving the fish tank out is not an option would Jill ( my oscar ) be ok in a 20 gallon tank that has filtration and a heater for that span of time ?

  • Wow whats happening to your house. How bigs the oscar?
  • She is about 6-7 inches the house is being treated for some not so friendly guest if you know what i mean boy was i pissed when i realized about a week after buying the house.
  • Termites? Glad we dont get them in the uk. I would’ve said ur oscar would be fine in there temporarily. I don’t heat my tank that warm to save electricity on my bill.
  • No bed bugs unfortunately. We are buying on contract from my husbands boss. He didnt know about the issue but has offered to pay for any related cost to get rid of them.
  • I’d used some water from your big tank to fill the 20… she’ll be ok for a day 🙂 best of luck on the bed bugs…
  • use at least 50 % water from you current tank. My friend had already done like that without any problems.
  • As long as that tank is cycled you should be fine, remember the new tank will spike because it is getting a large fish into it, keep an eye on the ammonia spikes and nitrate spikes, you should be good though if its only for one day. Your oscar will act funky by the moving from one tank to another then again back to the old, he will stress but that’s to be expected just in case you did not know.
  • Be sure to bring the current filter with the biologicals and keep the inserts wet with current tank water too. Then run the used filter so no small cycling and then bring home wet too.

Do Oscar Fish Need a Heater

Posted by Nate H: What is that in Celsius??? I’m a bit lost with this Fahrenheit talk haha

  • My Oscar loves it around 24 c
    He becomes real lazy and lays on the bottom if I go up around 28.
  • I run both my oscar tanks at 28c and both are thriving.
  • 300w aqua nova heater set at 28 degrees C
  • You can also run a bunch of smaller heaters that work together. A lot of people forget that. It’s almost safer than running one large heater though could fail. What happens if it fails? Your fish could die.
  • These fish are very tough.. if you heater fails the fish is not going to die if your tank is in a house that is somewhat “normal” temperatures.
  • RANT: Keeping a fish as a pet is more than a pet it’s a hobby, each and every fish has different requirements in order to live and thrive. It’s work, lots of research. You can’t just get a tank put a filter on it and a heater add fish and expect it to work, it’s not a puppy, they are fish and depending on the type they can be sensitive to elements that would not effect humans, do not just jump into it with no knowledge of this hobby.good luck and happy fish keeping.

Posted by Natalie Y: How often do you feed live and what do you feed? I know too much live food is a big no and so is feeder fish bc of disease.

  • Stay away Feeder gold fish they are high in fat content, feed him a quality pellet as a staple food , if you feed live food use guppys or neon tetra ect, a tropical fish, only feed one a week if that and quarantine the feeder fish for a couple weeks, I would recommend getting a small tank to quarantine feeder fish or even to breed them, my Oscar gets one neon tetra a month. I feed him a couple peas each day to be sure his digestive system is not getting clogged, feed him cooked carrots , krill, baby shrimp, grapes, strawberry, just mix it up, any questions on a food ask at this page,,my Oscar is still a juvenile and I feed him small portions all day.
  • This tank has been set up for almost a year now, we had a bunch of platy/guppy/molly/female bettas in there before, but the heater malfunctioned (it sort of like exploded/cracked?) And killed all of them. I put all new water in there after that happened, and it’s been sitting with the filter(precycled media)for almost 4 full weeks now. I’m still unsure if I should continue to wait or when a good time would b to get an oscar. We are getting a juvenile. Neons are small enough for them?
  • I think we want an albino tiger. Is long as my parameters are still fine next week we may get him then.
  • Personally I don’t recommend live feeding there are plenty of complete pellet foods out there, my oscar likes a bit of cucumber for a treat.
  • I feed live shrimp 2 times a week and pellets and lots of fruit and veg daily.
  • **ADMIN Alert: This is the wrong place for this topic. Should have been posted in our Food and Nutrition section.