Hi i'm kiran.I'm from Malaysia..My question is does heating the aquarium a must in my oscar's tank??

well, since you live in a tropical climate, you could quite easily keep the Oscars in an outdoor ponds without any heating I would have thought. I suppose it all depends on how warm your house is, most people in warm climates have air conditioning keeping their house at around 20°C. You probably would need a little bit of heating in your tank as Oscars should be kept in a temperature of between 21°C and 30°C, 28°C being the optimum I would say. However, if your house is extremely warm, you might just get away with not needing any heating. However, if you have other fish that require warmer water, you still may need heating

Thanks admin ..I keep my tanks in the living room where there is no aircond..I have a pair of red oscars 5.5 inches,a pair of tiger oscars 2 inches and three plecos in a 4 feet tank .I'l switch in to a 6 feet tank when i move out to a new house in november this year..