Dragon gobies    5/21/07
I know that there isn't much info on these fish but I know that more is  being discovered.
<There's actually lots about these fishes in the aquarium press. Take a look at the Aqualog brackish water fishes book, or perhaps my one from TFH. Goby scientist Naomi Delventhal covered this species in considerable depth in her chapter on gobies.>
I went to Wal-Mart (yes, bad idea, but I had to rescue  them from there) and bought 1 dragon goby, a 10 gallon tank some rocks  and plants.
<10 gallons far too small. A healthy specimen will reach 30 cm or so within the first year, and up to 50 cm when fully grown.>
Cleaned all and put him in. At the store he was all swimmy but once he settled in he became secluded (which I know is common) what I'd like to know about are his uncommon traits. The water is not brackish, yet he seems to be doing fine.
<These are indeed hardy fish, and will tolerate freshwater conditions for long periods. BUT NOT FOREVER.>
His tank mates are a snail, a Pleco, 12 swordtails (male and female), a very docile female crown beta that itself is very social, and some unknown number of ghost shrimp.
<None of these fishes are really suitable, except maybe the swordtails, which will do okay in brackish water at SG 1.005. Swordtails don't like brackish water, but at low salinity it won't harm them.>
Now, I didn't notice him eating before, but noticed he's been living for a few weeks now and my shrimp population is dwindling...
<When starving, dragon gobies will eat shrimps and small fish. Their normal and preferred diet is a mixture of infaunal invertebrates (worms and insect larvae, for example) plus algae. They also filter feed from the water (live brine shrimp are ideal). It is likely you are not giving the goby enough food to eat, and since he's hungry, he's eating what he can. Bear in mind that when properly cared for these are NOT PREDATORY, and people have kept them with even guppies and not lost any fish.>
So, someone suggested I feed him algae wafers, so I did which he seems to like. (He does the whole gulp and inhale nibble thing).
<Quite so. The little teeth in his mouth are for scraping algae from rocks. Try offering some fresh algae, e.g. sushi Nori, and see if he goes for that.>
My questions being,
One: if my swordfish mate, will he eat the eggs?
<Swordfish don't lay eggs, they produce live babies. If properly cared for the goby will ignore them, but if hungry he will eat them. But your swordtails will do that, too.>
Two: even though he is doing ok in freshwater, should I put him in brackish anyway?
<Yes, he needs a bigger, brackish water tank. At least 30 gallons, and ideally 55 gallons.>
Three: I know this is asked a lot, but how can I mate the dragons (hoping for new info)? Do I just buy many and hope for the best?
<Not been done yet, and probably complex. Many of these brackish water gobies lay eggs in burrows but the baby fish are planktonic, drifting around in the sea for a couple of months. Anyway, the first step is getting a group of them. They are territorial. In  a big tank people do keep them in groups, and they are quite fun like that. The fish "fight" by lining alongside each other, and push one another to see who is the strongest. Either way, each fish must have a PVC tube burrow of its own.>
Four: should I put my goby pal on a diet and try to feed him live food vs. wafers?
<He needs BOTH. They are filter feeders AND algae eaters, so doing just the one thing is wrong. A mixed diet of frozen bloodworms, live brine shrimp, and algae pellets is an excellent starting point. Watching them filter feed the brine shrimp is terrific fun -- they swim in the water, gulping the brine shrimp into their huge mouths like baleen whales!>
Thank you for your time!
-Dave
<No problems, and good luck.>