Beachrock Goby or Seep Goby
General information: These small gobies usually live in small pockets of water by the mangroves and rockpools that are filled from small freshwater springs occasional very high tides. Their habitat is in the wet dry tropics and during the wet season their water is fresh, as the dry season progresses the high tides change their water back to salty, even more salty then normal seawater. Their natural diet consists of small crustaceans, insects, other small invertebrates and some algae. They are reported to grow to about 6 cm in size. The best two photos are from Gunther Schmida, I drew the distribution map with the help of Google Earth. They breed in a similar manner to other gobies with the male cleaning a patch on a rock, log or other hard surface. The female lays a batch of small sticky eggs stuck to the hard surface then the male fans, cleans and guards them until they hatch. The water quality in the places these fish came from has not been measured by me but is either sea water or fresh rain water. An estimate of temperature range would be from 18 deg C to 35 deg C, Water quality I have seen these in sometimes appears quite dark in colour and influenced by decaying leaves and other detritus. In the dry season their pools are clean seawater after the spring tides.
Cultivation notes : In captivity they do well on pea and prawn puree mix, moina, daphnia, blood worms and tubifex or black worms as a supplement a couple of times a week. They will eat aquaculture crumble but dont seem to like flake foods. The water we keep them in is generally our bore water with some sea water added. If you use cooking salt from a supermarket to make up brackish water make sure there are no anti-caking agents in the salt from the information on the label. They are OK in very small aquaria and will go black with the gold edging on their fins when happy. If the water gets polluted in the aquarium they will climb up the sides out of the aquarium. They are OK in groups and are sometimes quite crowded in their natural habitat. If you give them some short lengths of small diameter conduit the larger males will take over the pipe and chase others away. They breed inside the pipe and the male stays and fans the eggs. They hatch in a few days, the fry are pelagic and very small. We have had them up to 30 days and watched them eat small motile algae. The fry mouths are less then 50 microns wide and need a small live food less than that size.
Distribution : They occur in a patchy distribution across the top of Australia in WA and NT.
Selling details : Sold individually at 3 centimetres total length.
Reference: Allen G.R., Midgley S.H. and Allen M. (2002) "Freshwater Fishes of Australia".ANGFA database - http://db.angfa.org.au