I'm sorry.
I didn't know there was a difference between coldwater and tropical fish. Can anyone tell me more about this? I don't know much about fish.
Well, I guess that makes sense. Tropical places are usually warm, right? Heh.
Edit: I was looking up a few fish, and I saw that some fish lived in conditions from 72-79° F (that's 'cold', right?) and some lived from 72-82° F (Well, my ait conditioner is that low, which is 'cool' in my opinion), so i'm totally lost to what your definition of 'cold' and 'warm/tropical' is. Help?
Okay, i'm reading on cycling. Gosh, i'm really confused. I'm sorry.
Fish come from different waters all over the world. It's actually a bit misleading to lump them into categories like "coldwater" and "tropical" as it's all relative and there is hufe temperature variance within those categories.
In short, though, some fish require temperatures that are warmer than our typical room temperature. This means these fish definitely need a submersible heater that will keep the water warm enough for them. The water wouldn't necessarily feel warm to the touch but the fish really feel the difference. Each species has a recommend temperature range based on where it is from in th world and what conditions it has proved able to live comfortably in. When buying fish for a specific tank we must make sure all the fish will be happy at the same temperature.
Tropical fish are very commonly avaliable and tend to be smaller than many commonly avaliable coldwater fish. This makes them a good choice for the beginner. The heaters are an extra cost but there is not particular skill upgrade from hardy coldwater fish to hardy tropical fish. It's really just a matter of temperature.
I would always recommend a heater in a coldwater tank anyway as while the room temperature will generally be warm enough for them, fish like a stable temperature and in a tank that is the same temperature as the room, the tank's temperature will jump about a bit depending on whether there are people in the room, whether the heating is on, whether it is night or day. Many heaters will go low enough to stay off 90% of the time unless the room gets too cold and then they'll come on.
While researching your fish you'll come across suggested temperature ranges and it'll start to make sense
So, to keep a 'coldwater' fish, you would need a cooling device for the tank? We live in a tropical sunny area (It's 92 degrees now at 5pm) and our air conditioner usually makes our home cold, but then it gets warm when we turn it off.