Ok so this is probably a weird problem and I feel just awful to be honest. I do everything I can for my two little oscars I'm an absolute freak about maintaining there water quality, I feed them worms and an extremely varied diet. So i got my 56 gallon tank from someone on craigslist. I've had it up and running for about 2 months. I have a synodontis catfish that's 7 inches in it that I got from her which was 7 years old when I got it and he's doing amazing, I added my two oscars a tiger and albino about 1.5 months ago and there between 3-4 inches now.

Anyways I didn't have an actual temperature gauge before. The heater had a thermostat on it which I stupidly believed was accurate and I set it to 78. So I checked it today and the temperature according to my thermometer was 90 degrees. I know this is horribly hot and it amazes me it has not done damage to my fish. They all seem extremely healthy, they eat like crazy they are fiends for worms. I lowered the temp down to about 82 according to my thermometer which I believe is accurate, I think the light might be heating it up an extra couple degrees but the heaters not turning on anymore i set it to it's lowest setting.

I guess I'm asking if anyone else has experienced anything like this because my 3 fish the two oscars and the catfish appear to be very healthy and growing just fine but it scares me that I might have damaged them in some way I can't tell yet I hope I didn't stunt there growth or anything. I'm an idiot for not testing the temperature of the water and trusting the heater I know just looking for moral support I suppose it kills me I failed my fish when I try so hard to give them the best so they can grow to there max potential.

I always end up with 2 or 3 thermometers on a tank to really trust the readings. It seems hard to get a good thermometer these days. If the temp was really 90 you are very lucky to have live fish....you must have good oxygen content in your tank. hope it all works out.

Cant say I have ever had a tank that hot before, but if they are still alive and not gasping for air then I think they should be OK. Watch your water readings.

And you do know you should be looking for a tank double that size, because in a few months they will be 6" plus - especially if your water is warm!

My advice would be to replace the heater, also your tank is hella over stocked

hi there


1. pls replace the current heater with a new one.
2. full aeration when heater is switched on.

90f is not in the danger zone by any means assuming plenty of oxygen so no worries there. Obviously want to get it down to around 80f though.

You are overstocked and need to upgrade to a 125gal+ asap for the longterm health of your fish.

My tank had been that hot before but I had two power heads blowing bubbles and about 6 real plants in the tanks to the oxygen content stays in there well. ( just had a really good heater and did not realize how high it could go)

Also had some convicts that got boiled by a janitor over break because he messed the heating up and I did not have any of that in there so they all died (water closer to 100)

So I have had them both ways live and die but you do have to upgrade on tank size or downgrade on fish if you want them happy and to reach full potential like I'm sure you do seeing as you are concerned!

Well my filtration system is rated just under 3 times what a normal 56 gallon tank would have the water current is quite strong so it does not surprise me that the oxygen content of the water would be very high. In total between the two filters I have there combined rating would be for a 140 gallon tank.

Don't worry I'm upgrading to a 125 pretty soon this is only temporary. There still pretty small I think they will be good for a little while.

A single full grown oscar 10-12" needs a 60 gallon tank. So a 5-6" Oscar needs a 30 gallons. With your syno being 7", it already needs 30 gallons of water to itself, leaving your two oscars with on 26 gallons of water.

Keep track of your water parameters and keep the nitrates below 20ppm, which can only be reliable done through water changes. If your nitrates are at 20-30ppm, you need to do a 50% water change for the week. If your nitrates are at 40ppm, you need to do at least two water changes of 50% per week.

If you are doing more than one water change at 50% a week, then you are already overstocked for your current aquarium.

honestly, in a arge tank like that, you need a big and high wattage
heater to attain that temperature. while you set it at desired temp,
the heater works higher while the temp is not attain.... the reason
you found it at 90 deg F... the surrounding remains lower than the
target range temp...