Bicolor Dottyback (Pseudochromis paccagnellae)
The half purple, half yellow fish in the above You Tube video is the bicolor dottyback (Pseudochromis paccagnellae). It is somtimes called the royal dottyback. It is a brilliantly colored marine fish from the Indo-Pacific.
This fish is very similar in coloration to the Fairy Basslet (Royal Gramma). However, the bicolor dottyback is even smaller than the fairy basslet. The bicolor dottyback reaches a maximum adult size of only 2 inches (5 cm) in length.
Bicolor Dottybacks are Very Aggressive Fish
Despite their small size, these dottybacks can be very aggressive as you could probably tell from the video above. Bicolor dottybacks are very territorial and they are also known to nip the fins of other fish. Because of their aggressive and bullying nature they should never be kept with small, timid fish.
You should provide plenty of hiding places in their aquarium. Bicolor dottybacks can usually be kept in reef tanks, but they do sometimes eat small shrimps.
The brilliant coloration of bicolor dottybacks sometimes fades in captivity. This is most likely due to dietary deficiencies. Provide them with plenty of well-established live rock for them to graze on. In addition, feed them aquarium fare for omnivorous marine fish, mysis shrimp, vitamin enriched brine shrimp, and finely chopped seafood and squid.
Bicolor dottybacks can usually be purchased for about $12-15 each.