There are so many popular tropical fish that it's hard to narrow it down to a short list, but here is a list of my favorite fish for beginner aquarium tanks:
Guppy (Poecilia reticulate). The Guppy is a great first time fish because they're easy to feed and care for. They provide some nice color and variety with their tail shapes. Guppies are also relatively easy to breed in aquariums.
Green Swordtail (Xiphophorus helleri). The Green swordtails can hybridize with other fish so think twice before putting them into a community aquarium.
Platy (Xiphophorus maculatus). This is another good first fish; they like to eat algae and they bear live young.
Planning your Tropical Fish Aquarium
As you design your tropical fish tank, consider the following styles that you can go with:
Community Aquarium is where you'll have a number of different varieties of fish in as harmonious a setting as possible, including plants to give the aquarium a very natural look.
Dutch Plant Aquarium uses lots of plants in a much designed style (it should look like the aquatic equivalent to a formal garden). Very intensive and some critics believe that the fish take second place to the plants!
Absolutely necessary accessories when keeping tropical fish include the tank heater and the tank thermometer:
Heater. The most common type of heater for aquariums is a submersible heater that includes a thermometer. Design your tank so that you can place the heater close to an area where the water is circulated to help spread out the heat. Wonder how large of a heater you'll need? It depends on how much water you're trying to heat. As a rule of thumb, you'll need 5 watts per gallon of water.
Thermometer. There are two basic kinds: the internal that is meant to be submersed in the tank and the external that sticks to the outside of the tank. The internal submersed thermometer is usually a little more accurate. REMEMBER: You're keeping TROPICAL fish so the temperature of the tank water is of utmost importance.
