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    Blennies

    Bicolor blenny

    Ecsenius bicolor

    Also sold as Two-coloured blenny

    Good first fish

    Bicolor blenny (Ecsenius bicolor), photographed in the sea or an aquarium
    Photo: Brian Gratwicke, CC BY 2.0, via Wikimedia Commons
    Care level
    Beginner
    Adult size
    10.2 cm in aquariums
    Minimum tank
    114 litres
    Temperament
    Mostly peaceful
    With corals
    Reef safe with caution
    Captive-bred
    Wild-caught (captive-bred rare)
    IUCN status
    Least Concern
    Show volumes in

    How do you care for the bicolor blenny?

    Peaceful; may nip other blennies, small gobies and dartfish in small tanks.

    Feeding

    Herbivore with some meaty food.

    Needs algae-based foods.

    Tank and special needs

    Plan for at least 114 litres of water (the care sheet says 30 US gallons).

    Rockwork holes to perch in; lid.

    Corals and invertebrates

    Clam mantles and fleshy LPS if underfed (LiveAquaria).

    Which tankmates suit the bicolor blenny?

    One Ecsenius per small tank.

    Suggested order in a mixed tank: add after the first peaceful fish.

    More than one bicolor blenny

    Keep one bicolor blenny: two of the same species usually fight.

    Other fish

    Checked against the other 59 fish in this guide, assuming a tank big enough for both. Individual fish differ, so treat this as a starting point.

    Avoid together (4)

    • Lawnmower blennyBoth are blennys of similar shape, which is a common trigger for fights.
    • Midas blennyBoth are Ecsenius; close relatives defend the same space and food.
    • Tailspot blennyBoth are Ecsenius; close relatives defend the same space and food.
    • Striped fang blennyBoth are blennys of similar shape, which is a common trigger for fights.

    Take care (3)

    • Neon gobyBicolor blennies may nip small gobies and dartfish in small tanks.
    • Yellow clown gobyBicolor blennies may nip small gobies and dartfish in small tanks.
    • Scissortail dartfishBicolor blennies may nip small gobies and dartfish in small tanks.
    Usually fine together (52)

    Invertebrates

    Only the invertebrates with a known risk are listed.

    Take care (2)

    • Tiger tail sea cucumberA stressed or dead tiger tail sea cucumber can release toxins that harm fish; cover pump intakes.
    • Sea appleA stressed or dead sea apple can release toxins that harm fish; cover pump intakes.

    Corals and anemones

    Only the corals and anemones with a known risk are listed.

    Take care (18)

    • Hammer coralBicolor blenny may nip LPS corals, more so when underfed.
    • Frogspawn coralBicolor blenny may nip LPS corals, more so when underfed.
    • Torch coralBicolor blenny may nip LPS corals, more so when underfed.
    • Duncan coralBicolor blenny may nip LPS corals, more so when underfed.
    • AcanBicolor blenny may nip LPS corals, more so when underfed.
    • FaviaBicolor blenny may nip LPS corals, more so when underfed.
    • FavitesBicolor blenny may nip LPS corals, more so when underfed.
    • Chalice coralBicolor blenny may nip LPS corals, more so when underfed.
    • BlastomussaBicolor blenny may nip LPS corals, more so when underfed.
    • Candy cane coralBicolor blenny may nip LPS corals, more so when underfed.
    • Bubble coralBicolor blenny may nip LPS corals, more so when underfed.
    • GonioporaBicolor blenny may nip LPS corals, more so when underfed.
    • AlveoporaBicolor blenny may nip LPS corals, more so when underfed.
    • Open brain coralBicolor blenny may nip LPS corals, more so when underfed.
    • LoboBicolor blenny may nip LPS corals, more so when underfed.
    • GalaxeaBicolor blenny may nip LPS corals, more so when underfed.
    • Scroll coralBicolor blenny may nip LPS corals, more so when underfed.
    • Carpet anemones (Haddon's, giant)The carpet anemones (Haddon's, giant) can catch and eat small fish such as the bicolor blenny.

    These checks follow the reasons fish and invertebrates clash: same species or genus, similar shape, mouth size, temperament, food, burrows, tank size and the order they are added. Individual animals differ; every source agrees on that.

    Quarantine and health

    Standard.

    New fish are the most common way disease gets into a reef tank. Quarantine every fish in a separate tank before it joins the display, and choose a method that suits its tolerance of copper.

    Captive-bred or wild?

    Wild-caught.

    What does it cost in the UK?

    about £28. This is one UK retailer’s listing on 21 October 2026, not a market average, and every item was sold out on that day.

    Sources

    1. LiveAquaria (US retailer) care sheetRead 21 October 2026, read in full. Used for: stats, cautions.
    2. FishBase species summaryRead 21 October 2026, read in full. Used for: max length, IUCN.
    3. Kraken Corals (UK retailer) catalogueRead 21 October 2026, read in full. Used for: UK price.

    Last checked . How we check

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    Lawnmower blenny

    Salarias fasciatus

    Care
    Intermediate
    Adult size
    14 cm
    Tank from
    114 litres
    Temperament
    Mostly peaceful
    Corals
    Reef safe with caution

    Photo Dirk Godlinski, CC BY-SA 3.0

    Midas blenny

    Ecsenius midas

    Care
    Beginner
    Adult size
    15 cm
    Tank from
    114 litres
    Temperament
    Mostly peaceful
    Corals
    Reef safe

    Photo BEDO (Thailand), CC BY-SA 4.0

    Tailspot blenny

    Ecsenius stigmatura

    Good first fish

    Care
    Beginner
    Tank from
    38 litres
    Temperament
    Peaceful
    Corals
    Reef safe with caution

    Photo Rickard Zerpe, CC BY 2.0

    Striped fang blenny

    Meiacanthus grammistes

    Care
    Beginner
    Adult size
    13 cm
    Tank from
    114 litres
    Temperament
    Mostly peaceful
    Corals
    Reef safe

    Photo Haplochromis, CC BY-SA 3.0