What Kind Of Goby?

[brynneth]

Yesterday when the fish store was cleaning out some of their old tanks, they came across some very very small gobies which I subsequently bought. They are almost an inch long, and light grey (almost transparent), with two vertical stripes, one from eye to chin and one from tip of dorsal fin to stomach. Their dorsal fins are tall and spikey and curved, and with the black they make sort of a crescent. They also have a fine streak of gold on the front of their dorsal fin. They sort of suspend themselves motionless in the water for long periods of time, and they have the fused fin on their stomachs. Help? I really need to know if they are freshwater or brackish.

 

[nmonks]

They sound like Redigobius balteatus.

http/filaman.ifm-geomar.de/Summary/Speci...ry.php?id=11817

These are pretty standard issue brackish water gobies that can be kept very much like bumblebees.

Gobiologist Naomi Delventhal has this advice about mystery gobies: if in doubt, buy them. Most gobies are small, so they're unlikely to get more than a few cm in length. Freshwater species will do fine in slightly brackish water, so keep them at SG 1.003-1.005 in hard, alkaline water. Provide with small live foods or frozen substitutes, as most are predators. Provided lots of oxygen, as most gobies are intolerant of poorly oxygenated water.

Sleeper gobies (which don't have the ventral "sucker") tend to be bigger and often eat small fish, but you can expect most species of those to get 15-20 cm and need brackish water.

There are exceptions to these rules of course, but giant gobies and sleepers are very much the minority -- literally one in a hundred.

Cheers,

Neale