So you have finish your Aquarium and its now time to add fish in the aquarium. But some fish can be prone to sudden water chemistry changes so choosing a hardy fish is one step for beginners.
These days there are many tropical fish and Coldwater fish to choose from. Tropical Fish will require a temperature from 25°C-28°C (77°F-82°F) and Coldwater Fish will require a temperature from 11°C-23°C (52°F-73°F). So keeping a constant temperature is one step to maintaining healthy fish. Having a good heater and thermostat is one thing to keep the temperature inside an aquarium constant.
Now a days there are many Tropical Fish and Coldwater Fish to choose from but if you are starting this hobby it is a good idea to choose fish that are hardy first than move on to the fish that are harder to keep because new aquarium can have sudden water changes and some delicate fish can not handle sudden water changes.
There are many colorful and beautiful hardy fish to choose from these days. Hardy fishes like platies, guppies, tiger barbs, gold barbs, black widow tetras and mollies. These fish will do great in an aquarium that you just started. But remember that most barbs won't do well with slow moving long fin fish because they tend to nip fish and tiger barbs could get very aggressive with each other and to other if they are not kept in groups of 5 or more.
When keeping fish in the aquarium the good rule of thumb is 1 inch of fish per gallons of water. For example a 10 Gallons tank could keep up to 10 one inch fish or 5 two inch fish. Also remember to know which fish compatible with your fish or not.