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[piatotsini]

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[AMS]

In short, yes. All Brachygobius species (in fact all low-end "brackish" fish such as kingt gobies) primarily inhabits freshwaters in the wild, while occassionally venturing into slighly brackish waters (some fish species more than others). It has yet to be scientifically explained, but for some reasons or another almost all low-end brackish fish due better in slightly brackish waters in captivity.

So yes, you can keep them in freshwater. One problem though, they become very disease prone, especially to fungus and other tough diseases. Making the water hard and alkeline (about 8 pH) helps a lot as well.

Minimum tank size is 5 gallons due to their small size, preferably 10 gallons.

 

[nmonks]

I'm afraid I beg to differ in opinion with AMS. They don't need brackish water, and while they do prefer hard, alkaline water, they do live in soft/acid water in the wild.

I have tested this out myself and found them to be viable in freshwater tanks so long as the pH does not drop below 6.5, when mortality possible increases. It's difficult for me to be certain if pH was the factor, because there was a goby-specific bacterial infection making the rounds in my tank, and besides some of the bumblebees, it took some of the Awaous gobies and some of the Rhinogobius gobies. So whether some or all of the bumblebee deaths were down to the infection, water chemistry, or both, I don't know.

My bumblebee guru, Naomi Delventhal, a goby biologist as well as breeder, has written probably the best summary on the web, here.

However, as a default, and particularly for aquarists laking experience of gobies, keeping them in brackish water might make sense. These gobies can be difficult to feed, and keeping them in brackish water allows you to add brine shrimps without the shimps dying quickly. That way, the gobies can eat as much as they want. I've not seen fungus on any goby yet, but if it does happen, salt will help.

Cheers,

Neale

PS. Many people fail with fish medicines because they neglect to remove carbon from the filter. Carbon removes the medicine, stopping the cure from working.

 

[OohFeeshy]

So would the traditional '1 tbsp salt per 5g' prove beneficial then? And if you do keep them in slightly brackish, do you need to be extra careful acclimating them, or will the comparatively small SG change not be too much worry?

 

[nmonks]

So would the traditional '1 tbsp salt per 5g' prove beneficial then?

Should be fine. A little salt is probably better than none, though I honestly don't think there's that much in it, assuming the pH and hardness are quite high. But adding salt does no harm, and may do some good, so it's a good "belt and braces" strategy.

And if you do keep them in slightly brackish, do you need to be extra careful acclimating them, or will the comparatively small SG change not be too much worry?

Such a small salinity change won't phase them at all. If I was being especially careful, I might add the 1 tablespoon per 5 gallon water with each water change rather than all at once, but to be honest that's a tiny amount of salt, and should be well within their tolerances. Remember, brackish water around 1.010 SG is about 15 grammes of salt PER LITRE, or about 60 grammes per gallon. One tablespoon is ~20 grammes of salt (apparently) in other words moderately brackish water is 3 tablespoons per gallon, or 15 tablespoons per 5 gallons. Your 1 tbsp is obviously 1/15th that ratio, which will result in an SG of less than 1.001.

Cheers,

Neale