here are some fish that i like! i know most of them wont be compatable but here we go
platax tiera------------------------
Batfish--------------------- No they get to big
labaricus quadrilineatus
nemateleotris magnifica---------
Fire Fish----------------------Fine
pomacanthus imperator---------
Emperor Angel---------------No they get to big
gramma loreto-------------------
Royal Gramma---------------Fine
synchiropus splendidus----------
Manderin----------------------No - Need a mature tank
pterois volitans-------------------
Liofish-------------------------No they get to big
rhinecanthus aculeatus----------
Trigger (of some sort)-------Not Reef Safe & get to big
paracanthurus hepatus----------
Blue Tang---------------------Need more swimming space than a 20g offers
acanthurus leucosteron----------
Powder Blue Tang------------Need more swimming space than a 20g offers
naso lituratus---------------------
Naso Tang---------------------Need more swimming space than a 20g offers
zebrasoma flavescens-----------
Yellow Tang-------------------Need more swimming space than a 20g offers
heniochus acuminatus-----------
Bannerfish---------------------Good beginners fish but require a larger tank
amphiprion percula--------------
Clown---------------------------Excellant fish for this size of tank & a beginner
dascyllus trimaculatus-----------
Three Spot Domino Damsel- Territorial & aggresive
jamie