Emma Turner on a lovely black freshwater goby.
Scientific name: Mugilogobius sarasinorum (Boulenger, 1897)
Common name: Black Toraja goby, Sarasin’s goby
Origin: Lake Poso, Danau, central Sulawesi,Indonesia.
Size: Up to 8cm/3.2”.
Diet: These gobies require a variety of small meaty foodstuffs. Frozen Daphnia, Cyclops, mosquito larvae, and vitamin-enriched brineshrimp should all be taken with much enthusiasm. In time, they may also show interest in small sinking pellets/granules, and crushed flake.
Water: Lake Poso has quite an unusual set of water parameters. The lake is freshwater with a high pH (>8.0) but a low TDS (<80) and GH (6o). Temperature is 26-28°C/78-82ºF and sometimes slightly warmer in the shallows.
Aquarium: A mature well-filtered tank is necessary. The substrate should consist of soft sand, with ample resting places for the gobies such as pieces of driftwood — and the spindly Sumatra wood in the shops is ideal. Form plenty of caves from rocks/slate, and scatterings of cobbles/small pebbles.
Vegetation is fairly sparse in Lake Poso, so plants are not absolutely necessary — although they may make the tank more aesthetically pleasing. Species from genera such as Eriocaulon, Lymnocharus and Ottelia are reported from the lake.
This species is best maintained as a male-female pair. If more than one pair is to be kept in the same aquarium, ensure that there’s an abundance of visual barriers among the décor, and that the tank itself is spacious, otherwise the males may fight.
Tank mates should be peaceful and of a similar size. Adult specimens will prey on tiny fish.
It is not unusual to see these gobies hovering at a 45° angle just above the substrate.
Sexing: Sexually dichromatic. Well conditioned males will appear jet black with the fuller-bodied females showing a browner coloration in addition to some mottling.
Identification: M. sarasinorum can be told apart from congeners by this combination of characters: seven dorsal spines, eight to nine dorsal soft rays, one anal spine, eight to nine anal soft rays and 26 vertebrae.
There are 13-17 scales below the lateral line (transverse row), 17-25 small pre-dorsal scales which extend forward almost to behind the eyes, sensory papillae on head which occasionally form multiple rows on the cheeks, and the caudal fin is truncated to rounded posteriorly.
Availability: The fish pictured here was recently seen at Maidenhead Aquatics @ Crowland, Lincolnshire.
Price: On sale at £9 each.
This item was first published in the August 2010 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.