well heres a list of some small fish that would do well in that tank...the parrot fish might eat them though...maybe you should think about getting that parrot fish...and maybe just stick with the smaller ones....?
-neon tetra ( like to be in schools of 5+,get like 1 inch)
-blacklight tetra ( like to be in schools of 5+,get like 1 inch)
-glowlight tetra ( like to be in schools of 5+,get like 1 inch)
-rummy nose tetra ( like to be in schools of 5+,get about 2 inches)
-tiger barb (they get about 2-3 inches and are somewhat agressive)
-white clouds ( like to be in schools of 5+,they get about 1 inch)
-yellow gouramis (very peaceful and only get about 2 inches big)
-dwarf frog (bottom feeder, they dont get too big, bout 2 inches or so)
-loaches (come in many species and clean the tank, bottom feeder)
-mollies ( come in many colours and get about 2-3 inches)
-fancy guppies ( many beautiful colours and patterns, get about 2 inches)
-sword tails ( kinda like mollies and come in cool colours)
-ghost shrimp ( cool little guys that are see thru and get about 2 inches, they are bottom feeders)
-puffer fish ( you can get little ones that get about 2 inches )
-goldfish
-bala shark( get about 4-6 inches, but are really cool)
another option for your tank is maybe getting a big fish....i have a big tank with a gar pike in it...he gets about a foot long, and eats other fish....here are some options for bigger fish....this is if you change your mind about the small fish( they will get eaten if in the tank with any of the following fish)
-gar pike(depending on what species, they can get anywhere from 1-4 feet long, eats other fish)
-oscar( get pretty big, but are awesome)
-rope fish( looks like a mix of an eel and a snake, gets about 2-3 feet long but stay small in size, and they eat bloodworms/feeder fish)
-arowana (really cool looking fish, but get pretty big, eats feeder fish)
-rocket gar pike( cool looking fish, eats feeder fish)
- blue dragon goby ( gets about 2-3 feet long, has a big head/mouth and eats bloodworms)