Convict Blenny – Engineer Goby – Juveniles | Profile | Care

convict blenny
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The convict blenny, scientific name Pholidichthys leucotaenia, or goby or the engineer blenny/goby, is a marine fish from the west-central Pacific Ocean. It’s neither a blenny nor a goby, however is in actual fact considered one of two species within the household Pholidichthyidae.

Convict Blenny profile

The Convict Blenny can be generally known as the Engineer Blenny. It’s in a separate household from the gobies and blennies. Its markings change all through its life. Constantly, the colors concerned are darkish blue to black on white.

As a juvenile, the markings are horizontal, working the size of the physique. With age, they change into vertical bands.

Convict Blenny Fish Facts

Name: Convict Blenny (Pholidichthys leucotaenia)

Family: Pholidichthyidae

Range: Indonesia

Size: Up to 3 inches

Diet: Carnivore

Tank Set-up: Marine: Coral or rock, plants, sand

Reef Compatible: Yes

Tank Conditions: 72-78°F; sg 1.020-1.025; pH 8.1-8.4

Minimum Tank Capacity: 30 gallon

Light: Medium

Temperament: Peaceful

Swimming Level: Bottom

Care Level: Moderate

Reproduction: Egg Layer

Convict Blenny Description

A small eel-shaped fish, will probably develop as much as 60 cm (24 in) in size. Juveniles resemble the striped catfish Plotosus lineatus, which is venomous, having a black physique with a white dorsal stripe.

As they develop, the stripe modifications to white convict-style barring or recognizing within the grownup.


P. leucotaenia lives in shallow lagoons and on coastal reefs from the Philippines to the Solomon Islands. It’s usually present in colleges beneath ledges or around coral heads.

These colleges swim in such tight formations, they resemble a single organism.

Sometimes, the species is discovered within the aquarium commerce, the place it’s identified for disrupting all however essentially the most secure buildings.

DNA analyses present this species to be neither a blenny nor a goby, however a part of a separate fish household, the Pholidichthyidae.

Within the Solomon Islands, researchers beneath Eugenie Clark discovered juveniles rising from holes within the seafloor and adjoining coral reefs.

By day, these juveniles swim as much as 50 m (55 yds) from their residence burrows to feed on plankton.

At the finish of the day, all returned to the burrows, outstanding and distinctive behavior for larval fish.

Convict Blenny Feeding

Whereas their younger are out feeding, the mother and father eject mouthfuls of particles from the burrows.

In a single day as a lot as three kg (6.6 lb) of sand is perhaps collected and spat out of the outlet by the mother and father.

Analysis has revealed a maze of tunnels and chambers totaling a size of some 6 m. In the evening, younger fish dangle by their mouths from the roof of the tunnels by skinny mucous threads.

Will devour a variety of meaty fare together with Mysis shrimp, vitamin-enriched brine shrimp, chopped krill/prawns/cockle, and many others.

If reluctant to feed at first, use a turkey baster to direct some meals decrease down within the tank to the place the Convict Blennies could also be hiding in a cave. Feed small quantities three instances per day.

Adults could develop to virtually 60 cm (24 in), however by no means depart the tunnels to feed.

They regularly soak up mouthfuls of juveniles and spit them out once more. An inspection of grownup stomachs confirmed solely a green slime.

convict blenny

Convict Blenny Breeding

This species has been bred in captivity. Spawning is said to happen inside a most popular cave system, and kids can quantity 400+. The fry is protected by the mother and father for the primary 6 weeks.

Appropriate for aquarium

It needs to be stored in a 30 gallon or bigger aquarium with a sand lined backside the place it might make burrows.

It wants peaceable tank mates and loads of hiding locations. Small teams or pairs are inclined to do higher in an aquarium, however, must be launched concurrently to the tank.

The Convict Blenny has been identified to spawn efficiently within the aquarium setting.

Its food regimen ought to include a wide range of recent or frozen seafood, brine shrimp, and mysid shrimp. It needs to be fed not less than twice per day.

In this case, a “regular” aquarium is a reef aquarium with blended corals or a fish solely aquarium with a rough salinity of 1.026 (sg) and a temperature near 26°C.

Species requiring greater than a 4000-liter tank are thought-about not appropriate for residence aquarium.

Particular aquariums could cowl tanks with low salinity, sub-tropical temperature, deep sand mattress, seagrass, and many others.

Reef safe

All the time reef-protected: No sources point out that this species will hurt corals of different invertebrates.

Usually, reef-protected: Just a few aquarists have reported issues holding this species with corals and different invertebrates.

Reef protected with a warning: This species could also be a menace to some sorts of invertebrates.

Reef protected with luck: Most specimens will hurt corals and/or different invertebrates, however, you are perhaps fortunate.

Not reef-protected: This species is a menace to most corals and/or different invertebrates.

Convict Blenny Care

The Convict Blenny is a hardworking, sociable species that’s finest stored in teams of three or extra.

Juvenile markings intently mimic these of the venomous Striped Eel Catfish (Plotosus lineatus), whereas the cryptic adults are black with daring yellow stripes and blotches.

The tank should be spacious to accommodate these large-growing fish.

As they’re excellent diggers, do be certain that all rockwork is safe and can’t be undermined by their intensive tunnel digging; a technique of doing that is to ahead plan for these fish and place your rockwork earlier than including substrate to the tank.

Peaceable in nature, Convict Blennies ought to get on with most different fish within the aquarium, supplied that they aren’t sufficiently small to be considered ‘chew measurement’ and never overly aggressive.

Regarding invertebrate compatibility, bigger specimens will prey on decorative shrimp, worms, and crustaceans, and it’s sensible to put corals off the underside of the aquarium in order that they don’t change into by accident buried with sand in the course of the Convict Blenny’s digging exercise.

This burrowing behavior is fascinating to look at and may be very helpful in holding the substrate turned over.

Convict Blennies are ‘scale-less’ and as such don’t tolerate chemical therapies very nicely in any respect. It’s best to maintain on prime of water high quality to make sure that these aren’t obligatory.

It’s a disgrace that many sellers appear to retail Convict Blennies as single specimens; do attempt to save yourself a great sized group and they’ll reward you with some very attention-grabbing pure behavior.

To sum up: an intriguing marine oddball species, which might be a terrific addition to these giant peaceable aquaria which are without small inverts and tiny fish.

That is primarily based on a medium measurement animal, which you wish to preserve for a number of years.

It is perhaps doable to maintain smaller specimens for a restricted interval in a smaller tank. A bigger tank is perhaps wanted for fully-grown specimens.


“Hardiness” signifies how resistant this species is to illness and the way nicely I tolerate dangerous situations on the whole.

Some species would not deal with transportation very nicely, however, that does not imply that the species is not hardy beneath the appropriate situations.

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