Photo by Mika d’Eau
Nemateleotris sp. – Ptereleotris sp. (lat.)
There are currently 45 species of dartfishes they are rather small (<20cm/8in) with most of the species not exceeding 10cm/4in. These fish are found in the Indian and Pacific Oceans and prefer to live above sandy, muddy bottoms or rubbly slopes. All species possess a retreat burrow, but they do not make their own. Instead, they utilize those dug by worms, mollusks, shrimps, and other sand gobies. These burrows are also used as overnight shelters.
They are found at depths varying between 2m to 70m, depending on the species.
Named for their defensive burrow-retreating behavior and filamentous fin rays resembling flights found on a dart or arrow as well as their tendency to dart into any available retreat at the first sign of trouble, dartfish are small and peaceful fish whose brilliant colors make them excellent candidates for photographers.
Dartfish are commonly seen hovering over the substrate. Usually, they hover just above their burrow and as the name implies, they are quick to dart into their hole. They are seen singly or in pairs but occasionally four or five may be seen in a small group, but this is rare. They normally hover with their head in a slightly upright position facing into the current. The bright yellow dorsal fin appears to be used to signal each other and is often flicked up or down.
Dartfish feed mainly on zooplankton and as a result are mainly found in areas with a fair amount of current. They hover above their burrow facing into the current and wait for zooplankton to come to them. They make quick darting movements to grab passing plankton. Gut analysis of fire dartfish has revealed that they feed mainly on copepods in the wild.
Juveniles are frequently found in groups, which are often quite large with up to 200 individuals, but most species will pair up with a partner when mature. During breeding pairs are formed but very little seems to be known of their breeding habits other than they seem to form monogamous pairs. Some reports mention them keeping the eggs in the burrow tended by the males and others have them close to the burrow tended by both male and female.
