After a bit of searching I've decided that bumblebee gobies would be the best fit for my little 5 gallon (currently fishless cycling). I'm planning to keep three or four of them, let me know if this would be too many.

They're being kept as fw fish at the LFS, but I'm going to very slowly convert my tank to brackish so they can adjust. I've been trying to find what their "favorite" specific gravity is. Brackish is defined as anywhere between 0.002 and 0.020, but is there any certain range where they will be happiest?

I've also read that with bumblebee gobies as well as many other brackish species it's actually good to let the salinity vary slightly from time to time. Is there any reason that wouldn't be a good idea?

Also, being completely new to brackish systems, is it any harder to maintain favorable and stable water params (pH, kH, gH) in a cycled brackish tank than it is a cycled fw? Will converting a fw tank to brackish mess up the cycle at all? Might be a silly question but I want to make sure I wont have to cycle again.

I know they prefer live food, though I don't think this is going to be an option for me so they're going to have to settle for frozen or flakes. That being said, since they apparently like to "hunt" their food - sitting in one spot and snapping at food that floats by - some sort of scavenger seems like a good idea. Would a couple ghost shrimp or something make a good clean-up crew? Would they live in bw, and be left alone by the bumblebees?

I've asked a ton of questions so feel free to break it into chunks. Thanks!

I'll hit on a couple of your questions but can't do them all since I haven't had my hand in brackish before, either.

- Five gallons may or may not be too small. It's all dependent on how you set it up. Five gallons with five fish with enough pots or caves for each one to claim a home is doable. Gobies are territorial usually so if they don't have to fight for a home then less to worry about. But then again five gallons is pretty small and will mean more water changes and that you'll have to really watch your water parameters like a hawk. A small but sudden change seems harder for me to recover from in a small tank than say in a 50 gallon tank.

- Not too sure on if you need to have a flux and flow with the salinity but remember that most brackish systems are in deltas or marshes where the fresh water and salt water are meeting. With tides and all there will be stronger salinity at times than others. There are seasons also when it's going to rain a heck of a lot which means much lower salinity levels - keepers of brackish water fish use this to their advantage by diluting with fresh water to mimic mating seasons at times!

- Ghost shrimp should actually be okay for the most part in brackish water. The young have to go through a larval stage in brackish if I remember correctly. So it wouldn't be a far stretch.

- Feeeeeding time! Feeding an ambush predator can be tricky as you seem already aware of. A thought is to create a strong flow at the bottom of the tank so the water is constantly moving. Add some thawed bloodworms and they'll just keep dancing around the tank until eaten, I bet!

Good luck!

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very helpful, thank you!

I've been searching a little more and it seems about 1/4 marine strength (0.005-0.008) is what they like, but like you said they're apparently very adaptable as long as the changes aren't too abrupt. I'll have to keep that in mind about the hiding places, and I'm sure plants will help if I can find any that will grow.

About the water parameters.. What's the most natural way could I go about maintaining a healthy kH to prevent the dreaded pH drop in my tiny tank? If all else fails I've heard baking soda works - is it safe? (is there any specific kind or brand to use)? My tap water is a little on the acidic side anyway, and the BBG's are supposed to like their water slightly alkaline, so that should help with the pH itself as well. Would the adjustment be stable or would I have to be constantly micromanaging the pH and if I chose to use baking soda? (any input is appreciated.. though I might end up moving this particular question to a different area on the forum)

Hello,
Here are a few answers to your questions:
1. Three or four is fine for your 5 gallon.
2. .002 - .005 for Brachygobius xanthozona slightly higher .005 - .010 for Brachygobius nunus should be ok
3. Just let the tank drop a an inch or two, this will increase the salinity. Then fill with freshwater. The salt will stick to the sides of the aquarium and will recycle back into the water when you fill back up with freshwater. This freshwater introduction period will be your best shot at breeding them, especially if the freshwater is a couple degrees cooler.
4. Brackish is a little harder to maintain water parameters because salitnity levels come into play, but check levels often, and try to make your changes gradual in general.
5. They generally need live food. The exception is if you can get the pet store to feed them flake and see if any accept it in the tank. If they do there, they will probably do the same at your house after acclimating.
6. As Logan84 said, ghost shrimp will be fine, as long as they are large enough not to be swallowed.
7. A piece of slate or shale worked naturally into your landscape would probably be enough to keep the kh where you want it. Type brackish tank into google and click the images tab to give you some landscaping ideas, I saw quite a few in there had rock to keep kh up.

Hope it helps, I had a successful 30 gal brackish tank for quite a while a few years back. It was very rewarding, I miss it!

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-Kenny
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Thanks, that's a lot of information as well.

Would a few natural seashells or a piece of souvenir coral do the same thing as the slate?

Yes, they should work fine. Make sure the soft organic matter is off them by boiling them in a pot before you put them in the tank. Also, remember to check phosphate levels occasionally. Post some pics of the tank too, I am excited to see it!

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-Kenny
My Blog