You would love to get amused watching a fish that confuses with its appearance, not just once but as long as it ages, and it is none other than the Engineer Goby.

This fish resembles multiple species from Goby, or Blenny, to Eel or Coral Catfish, but the fact is that it is not categorized in any of these fish.

These are unique fish as they belong to the Pholidichthyidae family that owns only two species in its single genus specification.

The fish looks attractive and quickly adapts to the new environment without any fuss, but if you are particular about the tank’s cleanliness then this fish is definitely not for you.

Here you will find the complete details about Engineer Goby’s background, features, living standards, and ways to manage this fantastic fish.

Species Specifics

Basic Profile
Scientific Name Pholidichthys Leucotaenia
Common Name Convict Blenny, Engineer Goby, Pacific Neon Goby
Family Pholidichthyidae
Native Philippines
Average Life 8 – 12 years
Max Size 34 cm
Fish Type Saltwater
Color White with Blue or Black
Price Range 15 – 22 USD
Engineer Goby About

Origin And Habitat

The Engineer Goby or commonly referred to as Convict Goby, is a typical marine species and cannot sustain freshwaters.

These fish are easily found in the west-central Pacific Ocean region. The observers have located them south of the Philippines to the Solomon Islands.However, they are astonishingly away from the Australian continent.

It mostly dwells close to the sandbars or barrier reefs in the low depth regions and prefers to stay in groups around the coral reefs.

The adults always stay hidden among the corals or burrows in the sand. The juvenile Engineer Gobies, on the other hand, migrate out into the sea to feed on planktons.

Fact: Engineer Goby can shift three kgs of sand in a day.

Size of Engineer Goby

These fish are usually bigger when they grow into adults but look pretty small as juveniles.

The average size recorded when they are babies is less than 2 inches, but the adults unexpectedly reach a length of 13.5 inches.

A few researchers have also claimed to have recorded the full-grown Engineer Goby fish to be 24 inches in the oceans, but they rarely come out of the burrows.


This amazing fish demonstrates multiple personalities to match other aquatics and camouflage the viewers and keepers.

As a young fish, it looks like a catfish, but as they grow in size and shape, the body patterns appear as a Blenny or Goby fish with white stripes over a black base. Unlike the catfish, it does not possess sharp teeth in the mouth.

The Engineer Goby fish transmits into different color patterns and body shapes after becoming a complete adult. The white lines vanish away, while thick yellow lines appear perpendicular from head to tail, and the longitudinal structure starts to resemble an eel.

Fact: The drastic change to the striped pattern earned them the name “Convict Blenny.”

Average Age

The Engineer Goby lives a considerable life in the wild or in the aquarium.

The fish has a total lifespan of 12 years but, on average, completes 8 – 10 years comfortably in the Pacific Ocean.

They claim an equal life in the private fish tanks if given proper care, food, and favorable tank conditions.

Differentiating: Male/ Female

One of the most complicated factors with the fish is that they hardly show any identifiable difference between the male and female fish.

However, the researchers have decoded a way to pick the females from the group.

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The most significant way to find the specific male and female Engineer Goby is to notice the belly portion of the fish.

The fish with bigger stomachs are females. Thus you can identify the gender through the fish’s size.

Price of the Fish

Due to its conflicting appearance, the fish has gained massive popularity among fish lovers, and keepers or breeders make reasonable efforts to get a group of them in their home fish tanks.

The sale of Engineer Goby ranges around $15 for a juvenile species, but the selling price varies depending upon the age, size, and color.

Engineer Goby Care Guidance

Quick Details
Care Level Simple
Social Interactive
Predators No
Temperament Non-Aggressive
Diet Carnivore 
Breeding Easy

Food Habits

The Engineer Goby is a carnivores species, which means it only prefers animal meat as food, whether in the open waters or in captivity.

It is baffling to imagine a non-violent fish like this only hunting other aquatics to feed itself and ignoring vegetation for food.

Their nature often becomes a complication for them because they usually stay hidden inside the sand holes and miss out on most of their attempts at predation.

While in captivity, you can provide them with food once in the morning and evening. Here is a list of their favorite food items.

  • Mysis Shrimp
  • Artemia
  • Brine Shrimp
  • Shellfishes
  • Live Worms
  • Krill
  • Squid

Behavior & Temperament

The Engineer Goby is not just peaceful and friendly towards other fish, but is also timid. They spend most of their adulthood digging holes and hiding in such caves.

The elderly fish rarely interacts with other fishes and stay involved in their digging. The young ones often travel long distances during the day to find suitable food and return at night to their burrow.

It is an unusual behavior by juvenile species in the animal world where the fish moves around for food in the early stage of life. However, as it grows older, it tends to predate the potential feeds that come in front of the sand homes.

Due to the shyness, the fish often reacts cautiously to moving inside the sand. So, it is sometimes hard to attract them to the visible area, especially when several activities are happening.

At their younger age, the Engineer Goby are accustomed to moving around the coral reefs, mostly in schools. The synchronous movements of these several fishes appear as one big aquatic.

Fact: While the adults dig holes all day, the youngsters return home at night and hang themselves from the roofs of the holes with the help of their mouths using sticky mucus.

Reproduction in Captivity

These fish pose a simple process for breeding. Once pairs mature in the tank, they will mate without any instigating elements under suitable conditions.

Hence, the only issue is getting both genders of fish into the tank, as it is tough to identify physically. You must read the below-given instructions before planning captive breeding.

Essential Requirements

Therefore, it is advised for the breeders to arrange a separate tank of a minimum of 150 gallons in volume and put about 5 – 6 mature Engineer Gobies together for mating.

A reef tank would probably be a perfect choice for mating because they can create caves similar to their natural habitat. You can also use rocks or stones with holes.

Fact: These fishes cannot reproduce before reaching the age of 3 – 4 years.

Mating and Spawning

Once you induce the fish in the tank, the mature males and females automatically interact with each other to form pairs and begin the mating and spawning process inside the caves.

Make sure to introduce them together in the tank to avoid bickering.

About 450 – 500 large eggs are spawned during the process, but nothing can be seen as everything takes place inside the holes.

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As the eggs hatch, the fry comes out of the holes and starts swimming in the water, which is very usual to their behavior in the wild oceans.

Engineer Goby’s parents protect the babies in a confined area. You can provide them with baby food such as brine shrimp nauplii, rotifers, or copepods.


The Engineer Goby does not have a complicated lifestyle. Professional breeders can successfully have them in closed spaces for a long time without any special care needed.

They are tough and adaptable to the environment and overcome the possibilities of the most common causes of illness. However, they may acquire a few abnormal symptoms, which are treatable.

  • They are sometimes observed dealing with “Saltwater Ich” disease. It is a parasitic disease commonly termed “out of the blue.”

It is usually not contagious and may appear due to their continuous stay in the sand holes, where parasites’ eggs hatch over their skin.

  • Another prominent factor is that these Engineer Goby do not have scales on the body.

Now the only problem is an injury, if occurred through rough substrates, corals, or while defending from predators, might take more time to heal than a fish with scales.

In these situations, the fish becomes vulnerable to infections if the concentrationbacteria or viruses in the water is higher than normal. It is hard to treat them since scaleless fishes are allergic to medicines.

You can begin with half of the dose while putting them in a quarantine tank and keep monitoring them.

Aquarium Care & Maintenance

Quick Stats
Capacity 200 Litres
Water Temperature 75 – 82Degrees Fahrenheit
Hardness Range 8 – 12 dKH
Tank Lighting Moderate light
Water pH Level 8.1 – 8.4
Tank Type Singular Tank
Substrate Corals, Soft Sand & Rocks
Brackish Yes
Salinity 1.020 – 1.025

Tank Size

The Engineer Goby is a slim-bodied but long-sized fish. The fish are usually smaller when they are juveniles but gradually grow while attaining maturity, thus requiring ample space for comfortable dwelling or swimming.

Initially, you can pet them in about 30 Gallons of volume space at their earlier stage. But as the fish matures, it can grow more than a foot, and thus, you need to get a minimum of 55 gallons of tank for a single fish.

In groups the fish feels stress-free and safe., so if you have more of these Engineer Goby, increase the tank size accordingly.

Aquarium Arrangements

The fish is slightly tricky to understand, considering their unusual temperament at different stages of life. You can put some of the suggested objects together and make the fish feel at home.


Engineer Goby is fond of living below the substrate levels and is a rigorous digger. If you get a rooted plant for your aquarium, then there are chances that it will get uprooted very soon.

The fish prefers to swim in the middle region. Therefore, you can introduce some floating plants like mosses into the tank, which wouldn’t hinder their pathway.


Being an introvert burrow dweller, they do not need much lighting in the tank. These are not nocturnal fishes but feel anxious in higher visibility.

Thus, you can choose moderate lighting systems such as LEDs in the tank.


One of the essential elements in the tank with Engineer Goby is the thick substrate, prominently sand or mixed with gravel. The fish requires explicit sand since it is a habitual digger and spends most of its time making burrows.

You can also put a few rocks with holes for making hiding spaces, but ensure that they stick to the place; because the fish, while digging underneath the stone, may hurt itself.


The fish is a natural dweller of the oceans and is comfortable surviving adverse waters. But still, in fish tanks, you can smoothen the environment by keeping a moderate water filter, which will also help oxygenate the water.

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Décor Items

The Engineer Goby is a firm-built aquatic animal to be kept in aquariums and tends to destroy or damage anything that irritates them.

So, any artificial item kept in the tank may get displaced soon, mainly because of their burrowing habits.

Tank Water Specifics

The fish is known for its low maintainability, and adaptable nature and hence is preferred for beginner fish-keepers.

But you must consider the water parameters necessary to keep the fish healthy and active.

  • Maintain the water temperature between 23 – 27 degrees Celsius.
  • The suitable pH range for them is between 8.1 – 8.4.
  • The salinity of water should be under 1.020 – 1.025.
  • Manage the ammonia, nitrate, and nitrite should be lowered close to 0 ppm, though the fish is not sensitive to their minimal quantities.

Tank Mates of Engineer Goby

The Engineer Goby is usually found busy in its world of sand digging, but otherwise, they are harmonious and socializing in nature.

But while inducing them in any community tank, one must remember that they are carnivores in nature and can predate on small, slow-moving fishes. Hence, it would be best to avoid Small Shrimps, Firefish, Moray Eel, etc.

You can put together some of the following given aquatics as compatible tank mates.

  • Banded Coral Shrimps
  • Arrowhead Crabs
  • Clams
  • Large Crustaceans (Starfish, Snails. Sea Urchins, Invertebrates)
  • Angelfish
  • Clownfish
  • Tangs
  • Dwarf Lionfish
  • Damselfish

Frequently Asked Questions

Is Engineer Goby Reef Safe?

Yes, if you plan to induce coral reef setup into the tank, you can surely do this while following certain precautions.

The fish does not tend to harm the setup, but the whole thing may get dismantled while digging. Therefore, keep the reefs securely and monitor the tank to alter the setting when needed.

Are they Aggressive?

They are pretty calm, cordial,and never show any hostile temperament towards other aquatics in the aquarium. But their natural food habit is meat-eating, and one cannot expect them to spare the small fishes in the tank even when hungry.

Thus, the Engineer Goby should be provided enough food, or else they can naturally attempt to kill and consume small mates in the tank.

Do they shed skin?

The Engineer Goby never sheds skin. However, keepers enquire about a plastic-like material floating in the water, which is not skin, because there aren’t any injuries or blood loss observed.

Instead, the fish produce mucus coating to cover the body, maybe to protect from injuries, which often gets detached to release into the water.

Can Engineer Goby and Snowflake Eel live together?

Snowflakes are stinge predators and eat everything. They are about 20 inches in length, which is almost double the size of Engineer Goby. But because of their contrasting features, the fish lovers wish to pet them in the same tank. Here are a few critical points one should consider before being decisive.

The Snowflake Eels possess a short-tempered nature, which makes other serene, smaller fishes get terrified, and hence experts advise not to keep them as mates.

But a notable fact is that they rarely indulge in grudges since the Engineer Goby get nervous and tend to run away from problematic situations, while the Eel may find itself too big to deal with them.

How do you differentiate between the Goby and a Blenny fish?

Though both the fishes look identical, there is a considerable difference between the two fishes notified by the experts.

  • The Blennies lay down in a curved order, while the Gobies prefer a straight posture.
  • The Blennies have minute tassels over the head, similar, but Gobies have a plain head.
  • Blennies can only survive in the freshwater region, while Gobies prefer saltwater.
  • The Blennies have an elongated tail with minute dorsal fins, while Engineer Goby has a straight body without any separate structure defining the tail.


The Engineer Goby is one of those aquatics you can bring home without thinking twice. They quickly familiarize themselves with the tank mates and start finding their dwelling space in the sand.

The fish looks gorgeous and appealing with its color formations and puzzles the viewers due to its matching personality with other fishes.

They are not overtly expensive in the fish market, and one quickly gets them as a single fish or a whole school of them.

About the Author

Victoria Lamb

Victoria is a freshwater aquatics specialist, fish keeper, and amphibian enthusiast. She has had more than 6 years of experience caring for aquariums and keeping several fish species, and her home boasts of 3 aquariums and a garden pond. Her goal is to educate fish owners on raising healthy and happy aquatic pets.

Career Highlights:

  • Has worked with several aquarium manufacturers as a consultant
  • Organized and hosted workshops on freshwater fish keeping at retail stores, educational facilities, and libraries
  • Released content for the amphibian community through her writings

Educational Highlights:

Bachelor of Science in Animal Behavior and Welfare

  • University of Lincoln, Lincoln, UK (2014-2018)

Writing Experience

Victoria has done ghostwriting for many aquarium and pet websites in the past. She has also worked for Canada's largest natural health magazine- ALIVE, with 300,000 monthly circulations as a freelancer. She had six published articles on animal behavior and welfare during her graduation for her thesis.

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