The native freshwater fish of Taiwan’s rivers, lakes, and estuaries comprise the most diverse group of vertebrates within the island’s terrestrial ecosystem. Taiwan Post issued a set of stamps on 10th March 2011 to introduce the beauty of Taiwan’s freshwater fishes. The first set of the series features Taiwan endemic fishes: Candidia barbatus, Opsariichthys pachycephalus, Spinibarbus hollandi, and Squalidus banarescui.
1. Candidia barbatus (NT$5): This silver white fish has an obvious deep blue lateral stripe extending from its gill cover to the base of its caudal fin. It typically measures about 6 to 12 centimeters long, but large examples can sometimes reach 20 centimeters. It is commonly seen in the upper stretches of rivers and their branches in western Taiwan. As a result of human introduction in recent years, it can be found in the rivers of the Hualien and Taitung.
2. Opsariichthys pachycephalus (NT$5): An adult male has some ten blue-green vertical streaks on the sides of its body and displays nuptial coloration in the area below its gill covers as well as at its pelvic, pectoral, and anal fins. Vigorous and ferocious, the species’ strong predatory characteristics make it a popular target for stream fishing. It typically measures about 8 to 15 centimeters long, but large examples can reach 20 centimeters. It is commonly seen in the rivers of western Taiwan.
3. Spinibarbus hollandi (NT$12): The fish has a medium-to-large mouth aperture and two pairs of barbels. The back of its body is slate gray and its sides are silver white. This large carp typically measures about 20 to 40 centimeters long. The largest examples can reach 60 centimeters in length. The stamp features a medium-sized adult. It can be found in the middle stretches of rivers in southern and eastern Taiwan.
4. Squalidus banarescui (NT$25): This fish is slightly transparent, with a black and gold lateral line on the sides of its body. There is a black marking that resembles the Chinese character for eight “?” on each of its lateral line scales. This small carp measures about 8 to 10 centimeters long. It can only be found in relatively deep and slow and slightly muddy rivers in central Taiwan.