The Engineer Goby: A Guide to the Popular Tunneling Fish.

Alison Page

Alison Page


Engineer Goby

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Marine fish are undoubtedly the most colorful, spectacular fish in the hobby. However, many of them are tricky to care for and very expensive.

But the Engineer goby bucks the trend, being easy to care for, beginner-friendly, and not outrageously pricey.

Read this guide to learn how to care for these beautiful, peaceful community saltwater fish.

The Engineer Goby – An Overview

Engineer Goby Info
Scientific name:Pholidichthys leucotaenia
Common names:Engineer Goby, Convict Blenny, Convict Goby
Origin:Indo-Pacific, Fiji, Indonesia
Size:12” long
Minimum tank size:55 gallons
Temperament:Social, peaceful
Care level:Beginner-friendly
Lifespan:Up to 11 years

Engineer gobies are also commonly called the Convict blenny and Convict goby. This can cause confusion since there is another fish called Convict blenny, Priolepis nocturna, which is a true goby.

Engineer gobies actually have their own family, Pholidichthyidae. In fact, these beautiful fish are closely related to the freshwater Cichlidae family, which includes oscars and angelfish!

Engineer gobies are carnivorous fish, preying on anything small enough to be eaten. So, although these are peaceful fish, they do pose a threat to smaller, weaker fish.

These fish are slightly territorial and sociable. In the wild, the gobies live in huge shoals many hundred strong, forming amazing, shimmering, living tunnels.

Construction Workers

The Engineer goby gets its common name from its constant construction habit. These fish have to have structures of some kind to burrow beneath and can become stressed if their habitat doesn’t provide that.


As juveniles, Engineer gobies have black bodies with a silver-white stripe, resembling the slightly venomous Coral catfish.

However, as the fish age, the horizontal stripes gradually morph into a more blotchy pattern until they eventually form vertical bars.

Engineer Goby Care Guide

The Engineer goby is easy to care for, making these hardy fish suitable for a beginner’s tank.

Tank Size

Engineer gobies can grow to 12 inches in length in a home tank, but they can grow larger in the wild. So, a 55-gallon aquarium is the minimum size required for adults.

Juvenile fish of two to three inches can live in smaller 20-gallon tanks until they mature.

Since these fish are carnivores, a larger tank with a greater water volume is recommended. In smaller tanks, the water parameters can become unstable, and dramatic shifts in ammonia and nitrate levels can occur if you overfeed your fish.

Like most eel-shaped fish, Engineer gobies are accomplished escape artists, especially when young. So, you need a tank with a tightly fitting lid to keep your goby safely contained. Lids with holes for wiring and pipework are all perfect escape routes for these lively fish, so always double-check that your aquarium is sealed.

Water Parameters

Engineer gobies are pretty tolerant of water conditions and can live happily in a setup with standard marine parameters.

The water temperature needs to be 75-82F to match their native equatorial habitat. Ideally, the ammonia and nitrite levels should be zero and nitrates below 20ppm. However, Engineer gobies aren’t especially sensitive to low levels of those compounds.

Tank Decoration

Engineer gobies get their name from their habit of constructing expansive tunnels underneath and throughout coral rubble.

In the wild environment, these industrious fish can shift up to six pounds of sand every day, creating tunnel networks many feet long.

Unfortunately, it’s not unheard of for Engineer gobies in captivity to become trapped or injured by coral rubble that shifts unexpectedly. Sometimes, the fish vanish without a trace for weeks, having become trapped, only to be found starved to death.

So, you need to use aquascaping adhesive to keep live rock pieces, hardscape, and coral frags firmly in place and prevent the Engineer goby from causing an accident and wrecking your aquascape.

What Substrate Is Best For Gobies?

Your substrate also needs to be a media through which the goby can easily dig. Sand is perfect for juvenile specimens. The youngsters can’t make tunnels, although the softer substrate does allow the fish to burrow into it.

If you have adult gobies, use gravel, coral rubble, or large-grained sand, as that holds better when the fish start constructing tunnels.

If the substrate layer is less than two inches thick, ensure that your coral and rocks are close to the tank bottom but not touching. That means it’s less likely that the gobies’ tunneling will seriously undermine your structure.

Safe Retreats

Finally, the gobies need rocky outcrops with cavities, holes, and gaps to hide in. Engineer gobies are more likely to remain above ground where you can see and enjoy them if they know there are plenty of escape routes for them if they feel threatened.

Health and Disease

Engineer gobies are scaleless fish that lack the protection offered by hard scales. So, bacterial infections can easily result if the fish are injured through fighting or digging.

Scaleless fish are also highly sensitive to certain medications used to treat common fish diseases. If you need to treat your gobies, always transfer them to a quarantine tank and use half the recommended dose.

Tank Mates

Engineer gobies are peaceful, sociable fish that like to live in groups. However, these fish are also opportunistic carnivores.

Any fish that are small and slow enough are at risk of becoming a meal for the gobies. Thin fish that fit easily into the gobies’ mouths are especially at risk. Small saltwater shrimp species are also popular snacks for the goby. However, adult specimens of the larger shrimp species, such as Banded Coral (Stenopus hispidus), should be okay.

Larger crustaceans, including Arrow crabs (Stenorhynchus sp.), are also too big to be regarded as a food source by the gobies. Snails, clams, starfish, and sea urchins are too unappetizing to be bothered by the Engineer goby, although these creatures will be seen off if they get too close to the goby’s burrow entrance.

Good tank mates for Engineer gobies include:

Most of the popular marine community fish get along fine with Engineer gobies, provided the fish are large enough not to be eaten. However, we recommend avoiding aggressive burrow-dwelling species, such as Moray eels.

Groups of juvenile gobies do very well in a tank setting, and adults also get along fine.

Diet and Feeding

Although Engineer gobies are carnivores, they are extremely easy to feed since they don’t need live prey. In fact, these fish are slow and not the most effective at catching food, so it’s often better to give them prepared frozen or fresh food.

Sinking carnivore pellets work well, and you can also give the gobies thawed bloodworms, krill, brine shrimp, mysis shrimp, and other similar foods. Fully-grown fish can take small pieces of chopped shrimp, fish, and squid, which you can give to the fish from feeding tongs.

How Often Should You Feed Engineer Gobies?

Since Engineer gobies are not particularly active fish, aside from their digging activities, one daily heavy feeding is adequate for them.

Breeding Engineer Gobies

Engineer Goby

If you have a large tank and plenty of patience, you can have a go at breeding Engineer gobies.

The main issue you have to deal with when attempting to breed them is that they are sizeable fish, so they need a large tank and the two sexes are almost impossible to differentiate.

In the wild, the gobies live in huge colonies, so you need to keep at least four to six fish so that they can form a colony and pair off naturally.

Engineer gobies are not sexually mature until they reach three to four years old.


Since these fish spawn inside the shelter of their tunnels, you rarely get to witness the Engineer goby actually spawning.

Condition the fish for spawning with plenty of high-quality meaty food. That’s really all you can do since the fish will do what comes naturally when they’re ready!

Eggs and Fry

When the eggs hatch, you’ll see hundreds of free-swimming fry congregating around the burrow entrance. When the fish become alarmed, they quickly rush back into their burrow.

Engineer gobies are good parents. So, provided that the youngsters are not threatened by any of their tank mates, the parents will do a decent job of raising them.

Engineer goby fry will eat frozen or live brine shrimp nauplii from day one, along with zooplankton and copepods. Once the juveniles are large enough, you can feed them flakes and small pellets.


In this section of our guide, we answer some of the most frequently asked questions about the fascinating Engineer goby.

Are Engineer Gobies Reef-safe?

Engineer gobies are reef-safe. The fish are harmless to anemones, corals, sponges, other sessile invertebrates, and clams. The only danger the gobies pose to your reef setup is through their digging.

If the live rock shifts, corals can tumble onto other corals, and because corals will aggressively sting each other, you could wind up with dead specimens if you don’t spot the problem immediately.

You must also remember that Engineer gobies are not safe around small shrimp and fish.

How Big Does an Engineer Goby Get?

Engineer gobies generally grow to around 12 inches in captivity, although they can get larger than that in the wild environment.

What Does an Engineer Goby Eat?

Engineer gobies are carnivores that need a meaty diet.

Fortunately, you don’t need to provide your gobies with live food. Frozen and fresh meaty foods, such as fish, bloodworms, brine shrimp, krill are sufficient. You can also feed the fish carnivore pellets and flakes.

Will Engineer Gobies Eat Other Fish?

Yes, Engineer gobies will prey on smaller, thin fish that will fit into the gobies’ mouths. These opportunistic creatures will also eat small shrimp.

Are Engineer Gobies Venomous?

No. Engineer gobies are harmless. However, the fish closely resemble the Coral catfish, which has mildly venomous spines that it uses as a means of defense.

Do Engineer Gobies Dig?

Yes! Engineer gobies get their common name from their habit of burrowing and constructing vast networks of tunnels in the substrate.

Final Thoughts

Did you enjoy our guide to the industrious Engineer goby? If you found the article interesting, please take a few moments to share it!

The Engineer goby is a peaceful, social fish species that can make a nice addition to a marine or reef setup. These fish get along well with other popular marine community fish, although you must avoid including any small, skinny fish that might be viewed as a meal.

You should also ensure that your live rock, corals, and hardscape are securely fixed in place so that the gobies’ burrowing habits don’t cause a collapse.

Do you keep Engineer gobies? Tell us about your setup in the comments box below.

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