Sleeper gobies the genus Butis (there are 6 recognized species) belong to the most original members of their kind. They swim around in the aquarium in every imaginable posture, especially often with the belly up, but also upside down or with the snout up. Thereby they imitate a floating piece of wood and are not perceived as a threat by their prey fish. The extremely voracious animals grow to a length of approx. 12 cm. Apart from fish, acclimated specimens also accept frozen food.
They are brackish water fish, which tolerate pure fresh water (but then pay attention to the pH-value, which should not drop below 8!) as well as pure sea water. Because of their salt tolerance, the species are very widespread in the Western Pacific region, being found from East Africa to India and Australia and everywhere in between. Butis gymnopomus (our specimens are from Indonesia) differs externally from the otherwise very similar B. amboinensis, B. butis, B. humeralis and B. melanostigma by the unstriped gill cover below the eye and the absence of a dark spot at the base of the pectoral fins. The rest of the coloration is extremely variable and the fish can change color in a flash.
Males have much longer extended posterior dorsal and anal fins. Although the goby often swims (or drifts) freely in the water, it is substrate oriented. When given the opportunity, it likes to snuggle up to a root or the like. Solid substrate is also used for spawning, such as a rock. The male takes care of the numerous, tiny spawn. The also tiny fry grows up in brackish water or sea; a report about a successful breeding in the aquarium is not known to us.
For our customers: the animals have code 408012 on our stocklist. Please note that we supply exclusively to wholesalers.
Text & photos: Frank Schäfer
