Being quite a vocal “netizen” on the reef newsgroups and mailing lists, I often get email asking me how to get sand-sifting gobies (eg, Valenciennea spp. (Sleeper Gobies)) to eat. I am well aware how difficult it is to get these amazing fish to thrive in a captive environment, so I thought I would share my successful experiences.
Keep in mind, you won’t have a hope of success with most of these species if they aren’t kept in pairs. If separated from their mate, they tend to stress, succumb to disease and eventually die. Occasionally juveniles that obviously haven’t paired up are available, but in my experience, they don’t tend to do well, either.
It should also be obvious (but apparently not from some of the email that I receive) that these fish must be kept in a tank with a sand substrate. Some of the larger species will do okay with fairly coarse sand, but they all do best with sand of a grain size of 2 to 4 mm. The sand layer should be a minimum thickness of 5 cm in my opinion (which incidentally coincides with about the minimum thickness for natural de-nitrification).
“My problem with gobies is they seem to just waste away after several weeks!”
It is usually very difficult to get sand sifting gobies to eat prepared or frozen foods. These fish need a lot of food to sustain their body weight and it amazes me that they even survive in the wild. It just goes to show how much there really is living in the sand on the sea floor. Unfortunately, starvation is a common problem with the sand sifting gobies. In the wild, they are not used to taking food from anywhere except the sand. You have to utilise this knowledge in training them to take other food. They are quick learners if you go about it the right way. Once they learn to take food from places other than the sand, they can be very lateral in their “thinking” and will actually gobble anything that will fit in their mouth (I constantly use the term “gobble” throughout this article as it cannot really be considered “biting”, “chewing” or “eating” until the fish actually determines that it wants to consume what it has taken into its mouth). Luckily, they will spit it out again if it is not suitable for them to eat. They don’t seem to have very effective teeth around the edge of the jaw, so I suspect that they grind up their food with specialised plates in their throats before swallowing it.
What I begin with in training my gobies is frozen brine shrimp. These tend to settle to the bottom when added to the tank and sit on top of the sand. If you can get them to fall somewhere near where your gobies are sand sifting, they will eventually pick one up in a mouthful of sand. It will be accidental, but they will sense the crustacean in their mouths and munch away. If you keep doing this for a 2 or 3 days, your gobies will eventually learn to identify that the orange spots (ie, the frozen brine shrimp) on the sand, are food. You will then see them intentionally scooping a mouthful of sand where a brine shrimp is sitting and then happily munching away. If you are having trouble getting them to feed this way, it may help to feed live black worms or blood worms at the same time as the frozen shrimp. When scooping the worms, they will also get some brine shrimp. I am pretty sure that sand sifting gobies know that wriggling worms on the sand are food, because they seem to go for these as soon as they see them whether they are on top of the sand or under it! Worms make up a large proportion of the animals in live sand, so it makes sense that the gobies would know to eat them. Unfortunately, they don’t seem to lateralise their thinking as much with worms, so you still have to use the brine shrimp.
Anyway, once you see that your gobies will consistently take the dead brine shrimp from the sand, you can start feeding live brine shrimp. They will immediately take any that settle on the sand and after a while, they will get the idea that the swimming orange dots up in the water column are food too (sometimes they are smart enough to realise right away that the swimming ones are food). Once you have got them to gobble the brine shrimp out of the water column, then you are on the home stretch towards the goal of getting them to take any prepared food. All you have to do now is feed some other type of food at the same time as some live brine shrimp. Sometimes this won’t work right away, so you may have to go back to feeding dead shrimp on the sand at the same time as the other prepared food. This way, they will scoop the prepared food on the sand as well as the dead brine shrimp and so, eventually learn that it is food too.
Eventually, they will gobble anything out of the water column without the aid of the brine shrimp signal. This can be amusing when they gobble the tail of a passing pipefish (gives the pipefish a bit of a fright until they get used to it but does no damage, not even a torn fin; the gobies spit the tail out right away) or the antennae of Coral-banded shrimp (the shrimp will very quickly let them know that that is not polite!) It can also be very worrying when they gobble a globule of sodium hydroxide floating by. They spit that out pretty damn fast, though! I was extremely concerned the first time this happened because I thought it may have burnt the inside of their mouth. I think their mouths are pretty tough, though, considering they sift sand all day long and indeed, it seemed to have no affect on them at all. They will also take pieces of algae floating past and of course they spit this out (these guys are definately not vegetarian).
All of the above takes patience and perseverence. Some stages may take longer than others to complete. Just make sure that you have succesfully completed a stage before you move on, otherwise it could take longer than necessary and these fish can’t afford to have a low nutrition diet such as brine shrimp (black and blood worms do offer more nutrition but as they are fresh water invertebrates, I suspect that they don’t provide a complete diet).
Also, once you have them feeding on chopped frozen clam, shrimp, etc, make sure that the pieces are small enough for them to swallow. Keep in mind that these things are soft and mushy in the wild and can be ground up pretty easily. Cooked shrimp for example is relatively solid food for these fish, so make sure it is small enough for them to be able to grind up. If they keep passing the food out through their gills, it means they can’t do anything with it (or they don’t like the taste, although in my experience, it is rare for them not to eat something edible). If you consistently give them large pieces of food that they can’t consume,
they will waste away!
“Should I quarantine them first or put them straight into my reef tank?”
First of all, let me tell you that I’m not a big fan of quarantining animals to begin with. I think moving them to a quarantine tank and then to the main tank is just one more stressful but unecessary move. In my experience, if your water quality is good, your new animals are not going to be harassed by tank mates and they are getting adequately fed, they will not be further stressed and therefore will not develop any disease.
You have to remember that most diseases are constantly present in the aquarium (definately whitespot) regardless of what you do to keep it clean, but your fish are able to fend off infection if they are happy (stress free). With gobies, most fish leave them alone when they are introduced to the aquarium (excepting of course, the “war mongers” of the fish world, the damsels). So, if you have good water quality, the only other thing you have to do is keep them well fed.
These fish, if kept in the dealers aquarium for any length of time, will usually be starving because there is generally no sand substrate and dealers don’t tend to attempt to train these fish to eat. So, when you get them home, I recommend putting them straight into your reef, so that they can get to feeding on the animals in your live sand. These animals are always burrowers, but will be too scared to start tunneling when first introduced. So, make sure you provide a flat piece of rock or an upturned clam shell for them to hide under while they get used to their new surroundings.
In conclusion, these are fascinating fish and make a great janitorial addition to a reef tank as long as you are prepared to spend some time teaching them how to survive in a captive envioronment. Make sure that they are kept well fed and they will provide an excellent talking point when you next have friends over; “Is that fish eating the sand?!”
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