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.>

Violet goby not eating   4/12/07
I have a violet goby.
<By which I assume you mean Gobioides sp., a large, greyish fish with a big mouth and tiny eyes, right? This is, as I hope you know, a brackish water fish, and needs 25-50% salinity to do well, i.e., SG 1.005-1.010. It will not do well in freshwater though, and will likely die kept under such conditions.>
It has been doing well for a good three months but in the last 3 days it has stopped eating and it's face has begun to look emaciated.
<This often happens in freshwater aquaria when brackish water fishes are kept in such tanks. So, first question, what water conditions do you have? If in freshwater, it is doomed, so please provide brackish water conditions. Aquarium tonic salt is *not* acceptable here, you need proper marine salt mix.>
I don't know what to do I try to put food near him so that he doesn't have to go far to eat but he just doesn't seem to care.
<What foods are you offering? These are algae eaters and filter feeders, so you need to give them algae and tiny, tiny foods such as brine shrimp however large and predatory they may look. They prefer to sift sand when feeding, and will gulp the sand, spit it out, and extract the goodies they find in it. They will also scrape algae from rocks (that's what their teeth are for). They also enjoy small or broken algae pellets, bloodworms, blackworms, and chopped earthworms. They have little interest in larger foods such as river shrimp or feeder fish, whatever the retailers sometimes suggest.>
Do you have any ideas of what to do?
<Well, first check the living conditions: you want brackish water, a soft, sandy substrate, and suitable burrows for the fish to hide away in (PVC tubes are ideal, but hollow ornaments will do fine). Secondly, the usual things: check the pH (at least 7.5) and the hardness ("hard" on whatever scale you use). Thirdly, reflect on its tankmates. Because they are essentially blind, they cannot compete with fast-moving things like scats and Monos. Far better to keep them with other slow-moving species such as fat sleepers and flatfish. Fourthly, do bear in mind they need lots of space. These are among the largest of all gobies, and your specimen has the potential to reach around 50cm/20 inches in length. Hope this helps! Neale>