Too many to list but some of my favorites include:
Freshwater.
Acarichthys heckelii
Apistogramma cacatuoides
Botia lohachata and sidthimunki
Corydoras barbatus
Epiplaty dageti
Iriatherina werneri
Pseudomugil signifer, furcatus and connieae
Rhadinocentrus ornatus
Cyprichromis leptosoma and Paracyprichromis nigripinnis
Lamprichthys tanganicanus
Protomelis species
Ophthalmotilapia furcifer and ventralis
Lepidogalaxias salamandroides
Saltwater includes:
Amphiprion akallopisos, nigripes, perideraion & sandaracinos
Anthias dispar, pleurotaenia & tuka
Nemateleotris decora, magnifica & helfrichi
Parablennius postoculomaculatus and most blennies, they are really cool characters.
Lysmata amboinensis shrimp
Periclimenes shrimp