Should i use a under gravel filter?

Question:

If not should I just use the filter it comes with and an air pump?

Answers:

Skip the undergravel filter. Some people swear by them but since you have a fluval you will not need to worry. Undergravel filters put oxygen "bubbles" in the water but all they do is just agitate the water, not oxygenate it. Good water flow is what releases Co2 in the water and allows O2 to enter. Since the fluval is a canister filter it creates great water flow.

Buying is an attitude that best at times be governed entirely by this tank

No just add an airpump and airstone.