Engineer Goby Burrowing Needs

[Wandering Albatross]

Good morning all, I'm considering a pair of engineer gobies for one of my tanks, because I love the eel look as they mature. Heard some mixed reviews on their compatibility, but in this tank their smallest tankmate would be firefish or dottyback sized. I know they get upwards of a foot or more, some claim they are harmless, others say they eat smaller fish when they mature. It's hard for me to picture any goby eating another fish, but these guys do grow pretty big by comparison.

What's the verdict, predatory or not? As for their burrowing needs, I have relatively fine 3-4" deep sand, on par with what my garden eels use in the other tank, but I'm worried about them being able to dig a burrow long/deep enough to hide a 12"+ body. Garden eels secrete a cement-like mucus that stabilizes their burrows, but the engineer gobies dig burrows differently. All my rocks in the proposed tank sit on eggcrate on the glass, so they can't get under them. Could I add some kind of under-sand cave structure in an area so it'll provide them a stable ceiling? Something like this? This one is only 7" long but you get the idea. Is there something better I can use? I could fill this partially with sand so they could hollow it out to their preferred thickness if needed.

• 

Also, there would be at least 1 melanurus wrasse in here, would the gobies bother a sand sleeping wrasse?

 

[JumboShrimp]

In terms of burrowing, I believe they act like eels on steroids! My friend has two in a 180-gallon.

 

[Wandering Albatross]

In terms of burrowing, I believe they act like eels on steroids! My friend has two in a 180-gallon.

I was under the impression they dug out burrows with their mouths. If they went tail first like the garden eels until they hit the bottom then went sideways that'd be okay, but all the images I've seen seem to show a more typical goby style burrow, maintained with mouthfuls of sand spit out the entrance, not a tube only wide enough to slither into when scared.

 

[JumboShrimp]

They will "engineer" (excavate under) all of your rocks in ways you were not expecting, is my understanding. Lol.

 

[Wandering Albatross]

They will "engineer" (excavate under) all of your rocks in ways you were not expecting, is my understanding. Lol.

My concern is their burrows collapsing on them, the sand is fiji pink grainsize. They cannot get under my rocks, the rocks sit on egg crate which sits directly on the glass, there is no physical way they can get under. They'd have to use the sand next to it, or pile the sand up in one of the bottom caves in order to dig it back out for their burrow. Unless their 'burrows' are more like when a wrasse sleeps in the sand then an actual excavated burrow. It's hard to imagine not needing to provide some kind of pseudo cave half buried for them to dig into, at least so they have a solid roof.

 

[619R]

We got one we’ve had for about 2yrs. About 12-14”. I’m thinking full grown. I’ve noticed him starting grow in girth lately. Yeah they will rearrange your tank for sure. The more sand you have the worse it’ll be. Mine will take to any cave I throw in there. But if you get any fish that bother them or kick them out of their spot they will throw a little fit and “rearrange”.

But luckily. If you just lets them dig a couple days and find their spot, that’s usually it. They don’t like to move from their spot usually. Just come out of their hole more as they get comfy.

Ours comes out every time I walk past the tank as if asking for food.

 

[619R]

Oh and ours has always been perfectly behaved. Never shows any interest in fish. Not even our yellow clown goby or blue goby.

They will pick up snail, hermits, and macro algae and take it about a foot away from their hole and drop them if they get bothered by them. But won’t eat the.

At least not yet