ok, i heat my my 180g tank by a external heater by hydor, it fits onto one of the return pipes from one of my external filters. i think they are great as the fish cant get to them and i find them great to heat the water maybe to good.

however i bought some new filter media and after i put it in the filter i went out all day. when i came home late last night i glanced at the digital temp gauge and the water temp was over 90 f.

when i had moved the filter to put the media in, the external filter heat setting knob must have rubbed against the wall and cranked it up to full!
fish are fine and temp is back to normal but could have been a disaster! so if you got an external heater be careful you dont do what i did, i also think they`d be a bad idea if you had young kids that may fiddle.

good advice to be careful.

90 isn't the worst, besides it moving up quickly.

You can treat Ich around that temperature along with salt. It not only speeds up the life cycle of Ich, but speeds up the Oscar's immune system as well.

Short term it is most likely just fine.

Long term, not sure. I know FL everglades have had Oscars in them, and with normal daily temperatures near or above 100 during the summer months ... I am sure they can deal with a bit of warm water, since at night it can also be in the mid to high 80s, and that is north central FL, north of the everglades.

of course aquifers may have a cooling effect, not sure. But it sure is hot here, and I have dipped in some lakes that have been warm to the skin in hot times (still cooler than the air temp and mean rays of the sun).


It is good to remember to keep an eye on our tank temps regularly though ... to catch even a malfunctioning heater (over-heating or stops working).

Glad your fish is fine

glad u caught it ontime,very lucky

yeah i wasnt to sure if 90 was to much, they seemed fine. lucky i got the spray bar bout an inch out the water so there is plenty of oxygen in the water.

90 is not something to worry about, an oscar will live fine at 90, it will however shorten its live if kept at that temperature long term

Good advice on the temperature setting when the adjuster is outside the tank. My discus tank felt colder than normal the other day, it was 28 when it should of been 30. I had accidently turned the temp down when cleaning the filter