The Spot Tail Dartfish, Ptereleotris heteroptera, also known as the Blue Gudgeon Dartfish, Blacktail Goby, or Blacktail Dartfish features an elongated pale blue/green body with a characteristic black spot on its tail. They thrive best in tanks with plenty of live rock, a sandy substrate, and a tightly sealed lid to prevent escapes. The Spot Tail Dartfish rarely becomes aggressive towards other species and is best kept with other peaceful species. They should be fed at least twice a day a varied carnivorous diet. The Spot Tail Dartfish is a wonderful tank mate and makes a great fish for beginner aquarists due to its hardiness and ease of care.