Is it recommendable to have an aquarium heater for freshwater fish?

Yes. All tropical fish need a tank heater. Only goldfish do not need a tank heater.

there are three sorts of tanks cold tropical and marine .
tropical is fresh water but has a heater and cold water is just that with out a heater.
cold water you would keep goldfish in

only if you have tropical fish like teetras, then it is important, if you have goldfish then you dont need one

If your fish are tropical(bettas, cichlids, tetras….), yes. It’s practically a neccessity that you get a heater for them. upper 70’s is the best temp for them.
For goldfish, koi or minnows, not really. They usually do well in temp’s lower than that of tropical fish’s….

Depends on what fish you plan to get. Goldfish are cold water fish and thrive at 60-74 F. White clouds and danios are minnows that can adapt to living in 64-74 F so these do not require a heater.

However, most tropicals have to have temps of at least 75 F, with 78 F being preferential. Then there are discus that have to have 84 F.

It is best to spend the money on a good heater if you plan on having a healthy tank of tropicals. Even if your room temp is 68-70 the problem is at night. Most people don’t get up at 3 a.m. when everything has naturally cooled to see what their temp tank is. Fish are very sensitive to temp changes of more than 4 degrees in a 24 hour period so the drop, while only slight, at night, over time would cause stress and even death. And then when seasons change it affects that tanks as well.

Good for you that you are doing some research before getting the tank. If you go to you can click on fish, then freshwater, and choose the fish that you are interested in. It will give you temp requirements for the fish you are looking for.

Make sure you cycle your tank before you add anything and then add compatible fish slowly and do not overstock. Happy fish keeping!

Good luck : )

Depends on what fish you plan to get. Goldfish are cold water fish and should be ok without one

if you get tropical freshwater fish, a heater is necessary, but coldwater fish, like goldfish do better in colder water. colder water holds more oxygen than warmer water. but tropical fish should have a temp. of around 75 or 76 degrees.