If you remember your geography, you know that tropics are a region of the earth that surrounds the equator. This means that tropics are warmer than other regions of the planets because of the sun.
If you decide to keep tropical fish you will have to keep your aquarium’s temperature “right” (just as it would be if the fish was in the wild). If the temperatures are not right the consequences maybe, the fish might stress too much and in worse cases your fish may die.
All this means that if you are not in a tropical region of the planet and you intend to keep tropical fish, you will need a reliable heater especially during the colder months. You see the thing is, tropical fish are comfortable in temperatures that range 76˚ to 80˚F that translates to 25˚to 27˚ C.
It is important to understand that fish species have different requirements i.e. some may require higher temperatures and others lower. Therefore before you buy fish that you intend to keep in an aquarium it pays to learn about the fish first. The idea is to know what the fish requires when and why.
Do some research–find out what temperatures your fish requires. The easiest to get this knowledge is by looking at tropical fish profiles, just start by Googling that and you will learn a lot of things about your fish.
Hot or cold
Note that, too much heat is bad for your tropical fish; it is also true to say that very low temperatures are bad for your fish. When it’s really hot in your region or in your home the first thing that you should do to keep your fish safe is to increase water circulation/ movement in the aquarium.
This will ensure that your fish don’t run out of oxygen, the problem with warm water is. Your fish’s metabolism increases thus it requires more oxygen. The real issue here is less oxygen is dissolved in warm water.
When the temperatures get really low in your home you will need a heater, to know the wattage of the heater you will need you will first have to consider the room temperature, once you know that you will be in a position to figure out how much heat the aquarium needs to reach the right temperature.
A good place to start is by checking heater wattage in relation to tank size, there are charts online that can help you top figure that out.
For example, if you have a 20 gallon fish tank it is recommended that you buy a 100 watt heater–this will keep the water temperature stable during the colder months of the year.
As mentioned above fish species are very different in that some can survive in warmer or colder temperatures for some time and others cant, if you know your fish you will know how long it can last in harsh environments.
When it comes to invertebrates that live in reefs things are very different, if the temperatures are unstable they will die quick. This means that reef invertebrates require more TLC, therefore overall the best thing to do is to buy an aquarium chiller and a heater. The chillers job is to lower temperatures and the heaters job is to raise it when it’s cold.