Based on my knowledge, there are at least 10 different commonly seen and rather popular species sold in pet shops. Although there are hundreds more different types as crossed reference with wikipedia sources, (some of which have not yet been domesticated in home aquariums) and regardless of which type of dottybacks, all of them bear one similarity in which they all have attractive strong coloration with some ranging from red mixed with purple to others having yellow and even striking neon. They also share the same territorial behavior that defines their trait but what makes it different from one species to another is that some can be less aggressive compared to the others. Dottybacks normally grow up to 2 – 3 inches in length, mostly doesn’t go much larger than that size but there are some unique species which can attain up to 6 inches in total measured from head to tail.
Generally depending on individual preferences, for me, I would prefer keeping those smaller ones but don’t undermine these little chumps as they could prove to be one of the most difficult pet fish to handle. I often find myself getting annoyed with one of my dottybacks pecking at my fingers while cleaning the tank and doing routine water changes. On another occasions, I even hear complaints coming from fellow hobbyist that their dottyback will pick on their clownfish until it has to be removed from the tank. Thus if your main idea is to set up a peaceful saltwater community aquarium, I would suggest you put aside your option to keep them together. Therefore, no matter how colorful and how cute they are, it is your responsibility to ensure that adding the new fish will not harm the others. So far, setting up a special single-species aquarium just to keep them should be okay as long as there are ample hiding spaces among the corals. However, there are some suggestions coming along saying that keeping your dottyback with damselfish is also fine but personally I haven't try that out. Others have even brought up the name of Heniochus wimplefish but I would advise you to be careful since you can risk getting your fish intimidated this way.
Below you will find a list on the collection of all the dottybacks that I’ve come across so far, together with their accompanying pictures. I hope you enjoy them as much as I do keeping them as a pet.
Less Aggressive (more suited for community aquarium)
Orchid (Pseudochromis fridmani)
Springer’s (Pseudochromis springeri)
Sankey’s (Pseudochromis sankeyi)
Orangetail (Pseudochromis coccinicada)
Yellow (Pseudochromis fuscus)
Highly aggressive (trouble getting along with other fish)
Diadema (Pseudochromis diadema)
Neon (Pseudochromis aldabraensis)
Bicolor (Pseudochromis paccagnellae)
Sunrise (Pseudochromis flavivertex)
Magenta/Strawberry/Purple (Pseudochromis porphyreus)
Dilectus (Pseudochromis dilectus)