Good fish for beginners based on size of tank:
10 gallons:
Firefish
Smallest
Gobies (ie Hi-Fin, Neon, Rainsford/Court Jester, Green Banded)
Barnacle
Blenny
Possum
Wrasse
20 gallon Long:
Ocellaris (ie Nemo) or Percula variety Clownfish
Geometric Pygmy Hawkfish
Yellow Watchman Goby
Pink Spot Goby
Decorated Goby
Pajama Cardinalfish
Royal Gramma Basslet
Pink Streaked Wrasse
40 Gallon Breeder:
Pygmy Angel aka Cherubfish (be aware there is some risk with
corals but they are one of the better behaved of the pygmy
angels)
Lubbock's Fairy Wrasse
Flame Hawkfish (just be aware that inverts and really small fish are at risk)
55 gallon (4 foot long tank):
Coral Beauty Dwarf Angel (a gamble with corals)
Flame Angel (a gamble with corals)
Smaller Halichoeres Wrasses (ie Yellow, Melanurus, Red-Lined, Christmas)
Flasher Wrasses
Smallest Fairy Wrasses
Standard 75 gallon:
Small Bristletooth
Tangs (ie Kole, Two Spot, Tomini)
One Spot Foxface
All Fairy Wrasses (ie Exquisite, Orange Back, Ruby Head)
5 foot long tank:
Yellow Tang (easiest Tang to care for but be aware they are on the aggressive side and can easily become a tank bully)