Diet, Diseases, Size, Mates and Tank

Greetings, fellow saltwater aquarists! We are delighted to present our complete care guide for the delicious Blenny Bicolore.

These quirky fish have a unique ability to perch on rocks or coral, giving them a comical and endearing appearance. They seem to have mastered the art of being part fish and part living statue!

We are delighted to guide you on this aquatic journey, so let’s dive in together and discover the secrets of happiness and well-being of the Bicolored Blenny!

Species Summary

Known as scientific Bicolor Ecsenius, the Bicolored Blenny is found in the waters surrounding Fiji, Sri Lanka, the Maldives and Indonesia. In fact, this fish is a familiar face among divers exploring exotic Indo-Pacific lagoons and reefs.

Author’s note: Because of its radiant lower half, this two-tone fish is sometimes called the Flame-Tail Blenny. These little champions really know how to chew!

A natural “worker bee” of the seas, the Bicolored Blenny is a comb-toothed fish with rows of tiny comb-like teeth lining its jaw to help actively remove algae from corals and rocks. Tank owners love how these fish help “clean up”.

With a price tag of around $16 to $30, and larger fish selling for up to $80, the Bicolor Blenny offers the opportunity to own beautiful, exotic fish at a much lower price than fish of corresponding magnificence.


The Bicolor Blenny can almost look like a slender eel scurrying through a tank if you look quickly! The long, slender body of this fish can make it look like some sort of ancient ray-finned fish from the deep! However, it’s simply impossible to misunderstand this fish’s unique body consisting of a blue upper half and an orange-yellow lower half once you look closely.

Author’s note: The Two-Tone Blenny is also identified by its single, ultra-long dorsal fin. He has large protruding eyes that merge with antennae to create what some might describe as an alien look.

Male and female bicolor blenny can be remarkably different. During breeding, the male undergoes dramatic color changes that turn it into a deeper blue. Males are also generally much brighter than females. The orange “flame” on the female’s half tail is much duller than the male’s.

The fins of males and females are also different. In fact, the way to know you’re looking at a male Bicolor Blenny is to look for extended fin rays. The female does not have this characteristic. In addition, the anal and dorsal fins of the male are larger. The male Bicolor Blenny is usually larger than the female.

A Bicolored Blenny resting on corals


Although this blenny can produce endless admiration, the fish is not known for an endless lifespan. The Bicolor Blenny typically has a lifespan of 2-4 years in the wild and up to 10 years in captivity. The shorter lifespan is mainly due to its lack of camouflage in its natural habitat, but in an aquarium with the proper care and attention, you can keep this fish for many years!


While the average size of a Bicolored Blenny is 3 inches, it is not uncommon for this fish to reach 4 inches.. Males are generally larger than females.

Bicolor Treatment with Blenny

The Bicolor Blenny can be considered a good fish for beginners due to its even temperament and basic aquarium requirements, as long as there is enough commitment to keep this fish healthy and thriving!

tank size

The recommended tank size for a Bicolor Blenny is at least 30 gallons.. Because these fish are used to jumping from pond to pond in the wild, they enjoy larger swimming areas. The larger tank size is also needed to house live rocks and hidden structures that the Bicolor Blenny needs to feel secure and contented. A cramped aquarium can make this docile fish aggressive!

Author’s note: Just make sure the tank is covered to protect those famous jumpers!

Water parameters

  • Water temperature: 75 to 80°F
  • pH levels: 8.1 to 8.4.
  • Water hardness: 8 to 9.5 dKH
  • Specific gravity: 1.024 to 1.025

Tank configuration

The Bicolored Blenny tends to cling to the bottom of the tank to satisfy its desire to recreate its natural habitat among rocks and corals. He will be attracted to hiding places and crevices. When creating a tank for a Bicolored Blenny, take the time to scatter the rock particles all along the bottom of the tank.

These fish also appreciate live rocks which can be used to create natural ledges and caves for hiding. Mature live rock is preferred over fresh rock because “seasoned” environments are healthier for the Two-Tone Blenny compared to sterile environments.. Remember that this fish will rely on algae attached to structures in the tank environment to thrive!

Are bicolor blennies safe for reefs?

There is a certain nuance to this answer. The Bicolor Blenny is technically a reef-safe fish because it is “mostly” a herbivore. There’s simply no reason for a Bicolored Blenny to go after coral when there’s algae on the menu! However, this fish will turn its appetite towards coral if not properly fed.

The Bicolor Blenny will also sometimes become quite aggressive to munch on coral if it is in distress due to overcrowding. Maintaining a good feeding schedule, growing algae, and keeping a tank uncluttered will ensure that the Bicolored Blenny does not pinch the coral.

Possible common diseases and prevention

Although the Bicolor Blenny is no more susceptible to disease than other fish, tank owners should still be cautious of the ever looming risks to Sea Velvet and Ich. The telltale sign of marine velvet is a thin coating of yellow or pale powder on the fish. Fish infected with Sea Velvet may also show signs of lethargy and respiratory distress.

Author’s note: If a Bicolored Blenny is itchy, it may be observed scratching its body against objects in the tank. Of course, the most obvious sign of ich is the presence of white salt-like spots dotting the gills and body.

The best way to prevent the spread of any type of disease in tropical fish is to quarantine new tank additions for up to eight weeks before adding them to an aquarium.. Always inspect new fish carefully. If a fish shows signs of illness, immediately place it in a quarantine tank away from all other fish.

Food and diet

The Bicolored Blenny feeds on algae. This fish will die without algae.

From its position at the bottom of the tank, a cheerful Bicolored Blenny will feast above all on algae. Adding microalgae as a food source is always recommended to increase the consumption of live algae. Although meat foods are fine occasionally, this Bicolor Blenny’s diet should consist primarily of fresh, frozen, and pelleted foods containing seaweed. The only sources of “meat” that Bicolor Blennies typically consume are brine shrimp and mysis (false shrimp).

Behavior and temperament

The Bicolored Blenny is generally considered a passive and accommodating fish. However, this rule disappears when this fish is grouped with other algae eaters. Yes, that includes the other Bicolor Blennies! It can also include dartfish, gobies, and seahorses. The Bicolored Blenny’s aggressiveness can actually “starve” other fish that need access to algae to survive..

Bicolor Blenny Tank Mates

While other bicolor blennies and other algae-eating fish are out, bicolor blennies can actually live happily with a wide variety of other fish. There is actually an exception to the rule when it comes to pairing Bicolor Blennies. If you can find a rare mating pair, you will usually have success with more than one Bicolor Blenny in a tank.

Some tank owners have also found that bicolor blennies are aggressive enough towards algae to prey on fish that simply look like other bicolor blennies. For this reason, royal grammas and bicolor pseudochromis should be included on the “no” list. Some fish that get along well with algae-obsessed bicolors include:

The Bicolor Blenny’s small size can make it vulnerable to bullying from larger fish. Although not common, it is possible for larger fish to prepare meals from the Bicolored Blenny. You may be able to avoid unnecessary carnage by separating bicolor blennies from eels (the ribbon eel is one of them), groupers, lionfish, pigfish, parrotfish and scorpion fish.

An Ecsenius bicolor looking for food


When trying to breed Bicolor Blennies, expect the dance to begin with a lovers’ quarrel. Pairs that mate are known to fight before they get down to business. Just let it take its course.

The telltale sign that mating is in progress is a color change for the male. You will also see the pair flee into hiding. A mating pair of Bicolored Blenny will delicately hide their eggs in the nooks before vigorously guarding the nest. The eggs hatch a few days later. The Bicolor Blenny’s reliance on hiding places during mating only emphasizes the need to provide a tank with abundant live porous rock.

The easy part is done, now for the hard work. As soon as you see the fry, you need to move them to another tank, otherwise they will become snacks. Then, make sure to do 10% daily water changes and feed them properly with tiny foods like rotifers and phytoplankton. With a bit of luck, you’ll get a few Bicolor Blennies yourself, because not all of them make it.


We hope this care guide has enlightened you about the wonderful world of Bicolor Blennies and provided you with the knowledge to ensure their thriving existence in your saltwater aquarium. Their unique ability to perch and entertain with their amusing antics make them a delightful addition to any aquarium, and their algae-eating behavior contributes to the health and cleanliness of your aquarium. Need more?

The companionship and charm of your Bicolor Blenny will reward you with endless joy and entertainment. If you want to learn more about other fish, try our saltwater maintenance guides and don’t forget to tag us on Facebook when you share a great photo of your aquarium!

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