There are hundreds of different kinds of saltwater aquarium fish. Some are quite difficult to care for and are best left to experienced marine aquarists. Beginners have a lot to choose from, though. Remember to buy tank-raised fish whenever possible.
Damselfish, which belong to the same family as clownfish, are popular because they are hardy. The blue reef Chromis, a shiny blue damselfish, likes to swim in shoals, or schools. Cardinalfish are known for being slow-moving and calm.
The different species come in impressive colors: fiery red flamefish; polkadot-tailed pajama fish; candy-striped cardinalfish with stripes running nose to tail; and long-finned, vertically striped Banggai cardinalfish.
More clownfish tank mates suitable for a 30-gallon aquarium
Valentin’s sharpnose puffer
Puffers are fish that can inflate their bodies like a balloon when they are angry or surprised. Most species of puffers grow too large and are too aggressive to do well in an average-sized aquarium, but the Valentini sharpnose puffer stays small – around 4 inches (10 centimeters) long.
This pretty, spotted-and-striped fish is known by several names, including “Valentini toby” and “black-saddled toby.” Its scientific name is Canthigaster valentini, and it is found in the Indian Ocean from the eastern coastline of Africa to Australia.
Spotted sharpnose puffers usually do not bother other kinds of fish, though they will eat invertebrates and may be aggressive toward other puffers. It is best to keep one puffer at a time in a fish-only aquarium.
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Flame Hawkfish
Hawkfish are small fish that live in coral reefs. Unlike most fish, they do not have the inflatable organ called a swim bladder, which allows fish to float. Instead of floating, hawkfish use their fins to perch upon coral so they can keep an eye on their surroundings. You may notice an aquarium hawkfish observing your movements, too.
Hawkfish got their name because they swoop down on their food catch, much like hawks. They are known as one of the easier marine aquarium fish to care for, though they are better for fish-only tanks.
Most hawkfish grow between 3 and 5 inches (7.6 and 12.7 centimeters) long, but some grow as long as 12 inches (30 centimeters). Two popular types are the flame hawkfish, which is bright red with black markings, and the longnosed hawkfish, which has a pattern of orange-and-white squares on its body and a pointy snout.
Yellow Watchman Goby
Gobies are bottom-dwelling fish that live mostly in the shallow parts of warm oceans. There are about 2,000 different species of gobies, and they come in an amazing variety of colors. Most gobies are only about 1 to 5 inches to 13 centimeters) long, though a few kinds grow to 1 foot (30 centimeters).
Gobies devote themselves to cleaning their surroundings – including fellow fish. Some gobies establish “cleaning stations,” where larger fish line up and wait for the gobies to eat harmful parasites off their bodies. Many species of gobies are suitable for beginning marine aquarists.
One popular kind is the tiny neon goby, about 2 inches (5 centimeters) long with a glowing blue stripe. Randall’s watchman goby (also called Randall’s shrimp goby) forms a special relationship with a certain kind of shrimp in the wild. In exchange for sharing the shrimp’s burrow, the goby watches for predators (hunting animals) and warns the shrimp when they are near. This kind of goby may burrow in the gravel at the bottom of the tank.
Royal Dottyback
Dottybacks are shy fish that often hide among the caves and crevices in coral reefs. They are usually about 3 inches (7.6 centimeters) long, and many species are available tank-raised. They come in an amazing variety of colors, as you can tell from the names of a few popular ones: the neon dottyback, magenta dottyback, orchid dottyback, and sunrise dottyback. Dottybacks are often good for beginning marine aquarists.
However, most dottybacks are territorial, which makes them aggressive under some conditions. It is best not to have more than one dottyback in a tank unless the tank is large enough to give each fish some space. It also helps if the dottyback is smaller than the other fish in the tank.
Mandarinfish
Mandarinfish are tropical fish that live in the coral reefs of the western Pacific Ocean. They are popular with experienced aquarists for their beautiful colors and patterns. Mandarinfish may have been named for the brightly colored silk Mandarin Chinese robes of the 1800’s.
Mandarinfish are small, peaceful, bottom-dwelling fish. They typically are only inches (6 centimeters) long or smaller, which can make them difficult to spot in their reef habitat. When they swim, they look a bit like tiny helicopters.
They move very slowly, using their fins to hover above the coral or ocean floor as they search for food. Mandarinfish have very specific dietary needs, so they are recommended only for expert aquarists.
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