This is a juvenile Polka-dot Boxfish, Yellow Boxfish, or Blue-spotted Boxfish. It's so cute! It's amazing that this little fellow will grow up to be an adult thats 18 inches (45 cm)!
The Polka-dot Boxfish, Yellow Boxfish, or Blue-spotted Boxfish has an almost perfectly shaped cube for a body. It is yellow or cream colored with dark-blue spots. As they grow older the body becomes more elongated and the color can change to different colors, but mainly a yellow-green. The spots turn white with blue rings around them.
For more Information on keeping this fish see:
Guide to a Happy, Healthy Marine Aquarium
Maintenance difficulty: The Polka-dot Boxfish, Yellow Boxfish, or Blue-spotted Boxfish is easy to keep. Boxfish are not challenging if you feed young specimens several times a day. Start with brine shrimp.
The puffer's teeth will continually grow throughout its life so you will need to supplement their diet with some hard shelled foods. Occasionally offering foods such as live ghost shrimp and various live snails will keep their teeth worn down.
Maintenance: Feed all kinds of live and frozen foods. Best to feed small amounts several times a day. We generally feed squid, shrimp (the same kind people eat), mussels, and all kinds of chopped up fish. Be sure to wash these foods thoroughly before feeding. Live fish will also be taken but should not be fed exclusively.
Habitat: Natural geographic location: Polka-dot Boxfish, Yellow Boxfish, or Blue-spotted Boxfish are found in the Indo-Pacific: Red Sea and East Africa to the Hawaiian and Tuamoto islands, north to Ryukyu Islands, south to Lord Howe Island. The Red Sea population differs slightly in coloration and has been known as Ostracion argus; closely related to Ostracion immaculatus from southern Japan. Southeast Atlantic: south coast of South Africa. Inhabits lagoon and semi-sheltered seaward reefs. Juveniles often among Acropora corals. Solitary. Juveniles expatriating to subtropical zone from the pelagic larval stage. Small juveniles secretive in narrow crevices. Occurs near shore in rock bottoms.
Foods: In the wild this boxfish feeds primarily on algae with a compliment of microorganisms, invertebrates, mollusks, sponges , sand dwelling polychaetes, crustaceans, foraminiferans, and small fishes.
In the aquarium you should feed all kinds of meaty foods and greenstuffs. A bottom feeder. Puffers are primarily predatory fish in the wild though they do graze on a bit of algae. This puffer will enjoy all kinds of meaty foods including shrimp, worms, clams, various mussels, snails, tunicates, and fish. They are not picky eaters and will quickly become adapted to a variety of prepared aquarium foods and an occasional algae wafer. Flake food is not recommended. Even though they may eat it, puffers will not thrive on it.