American Flagfish

1 Species Overview

The American flagfish is an upper-water fish with an aggressive temperament; when it attacks a target its swimming speed can reach 70 miles per hour and its striking power is especially strong. The American flagfish also has a very unusual shape, and because of its special body it is the fastest swimmer among animals.

Also known as: Flagfish, star-and-stripe fish

Latin name: Jordanella floridae

Chinese name: American flagfish

Distribution: Florida, USA

Kingdom: Animalia

Average length: 6 cm

2 Appearance and Physical Traits

The American flagfish is called the fastest swimmer among animals, normally swimming at 90 km/h. Although the dolphin is also a strong swimmer, it is not faster than the American flagfish. In fact, the flagfish’s shape is very special, which is why it swims so fast.

The American flagfish reaches 6 cm, with a moonfish-like body but a broad back and belly and a wide caudal peduncle. The head and snout are bluntly rounded. The caudal fin edge is straight. The dorsal fin is larger than the anal fin; the dorsal and anal fin edges are arched. Body color varies: red, pale yellow, blue, purplish-red, light or deep, bluish or reddish, covered with more than ten vertical star-dot stripes; the dorsal fin is covered with dark star dots, and the star-stripe pattern resembles the stars and stripes of the US flag, hence the name.

The American flagfish has a moonfish-like body but a broad back and belly and a wide caudal peduncle. The head and snout are bluntly rounded; the caudal fin edge is straight. The dorsal fin is larger than the anal fin, their edges arched. Body color is variable: red, pale yellow, blue, purplish-red, in light or deep shades, bluish or reddish, with the upper jaw protruding forward sword-like. On the blue-brown body are grey-white spots arranged in vertical rows like dotted lines. The first dorsal fin is long and tall, with a notched front edge; when raised it looks like a sail hoisted on a ship, or a waving flag. Hence the name flagfish.

The second dorsal fin is set apart from the first; the front spines of the first dorsal are about half the length of the middle spines. The body side has many pale spots. The first dorsal fin is especially tall and sail-like. The pelvic fins are long, with only one spine that folds into a belly groove, nearly reaching the anal fin. Except for the naked snout, the rest is covered with needle-like cycloid scales, mostly buried under the skin. The caudal peduncle is slender, with 2 short low ridges on each side. The snout extends forward, long and pointed like a sword. The pectoral fins sit low. The head and body back are blue-green.

3 Habitat and Living Environment

The American flagfish is also kept in captivity. In the aquarium you must pay special attention to tank size, because the flagfish can grow fairly large; a tank that is too small will halt its growth.

Since the goal is to keep a large fish, the principle is to provide a large space. But most keepers start with smaller or juvenile fish, partly because they are easier to get and partly because juveniles are cute. They overlook the fish’s potential and the later problems of an adult. If keeping goes wrong and the flagfish dies young, you will not see the bent body or stunted growth caused by cramped space. So before keeping a flagfish, study references to learn how big it will get and how much space it needs, and prepare a somewhat larger tank from the juvenile stage so you need not keep changing tanks. At first the tank may feel empty, but the large space does speed growth; fish that grow fast as juveniles tend later to grow faster, larger, and stronger.

Often large fish are kept alone in a big tank, both because of size and because adults are strongly territorial. In the juvenile stage, flagfish are small and people try keeping several together. The tank looks lively, but within one space there is competition for food and, for naturally territorial species, mutual psychological stress; this makes the large fish spend energy on chasing, fighting, and agitation instead of growth, slowing it down. For these two reasons many large-fish keepers buy fish only when already somewhat large or full-grown.

4 Feeding Guidelines

Keeping the American flagfish means attending to water and environment and also giving suitable food with balanced nutrition; this needs a scientific feeding method.

In nature the flagfish mainly chases small fish and insects, which gives ample balanced nutrition. Combined with long foraging and much exercise, and no space pressure, it grows evenly and strongly. The captive flagfish lacks no food, but keepers often fix on one favorite live food, causing nutritional imbalance. For balanced nutrition, mix different live foods. For example, in a month feed small fish once, shrimp twice, and insects once.