The Black Yellowtail Blenny (Ecsenius obsoletus) is a small, colorful species of blenny that originates from the Indo-Pacific region, particularly around the coasts of the Philippines, Indonesia, and Papua New Guinea. It is highly valued for its vibrant coloration and active, inquisitive behavior, making it a popular choice for reef tanks. Below is a detailed care guide and description of the Black Yellowtail Blenny.
Description:
- Size: The Black Yellowtail Blenny typically grows to a size of around 2.5-3 inches (6-8 cm) in length, making it an ideal candidate for smaller to medium-sized aquariums.
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Appearance:
- The body is elongated and slender, typical of blennies.
- The fish’s overall coloration is a dark black or dark brown, with a striking yellow tail that stands out against the darker body.
- The head is relatively large, and the fish has prominent large eyes and a slightly flattened face.
- The yellow tail is bright and vivid, providing an eye-catching contrast to the body’s darker tones. It is one of the most distinguishing features of this species.
- The dorsal fin is fairly long and continuous, with a smooth transition from the head to the tail. It is typically dark in color like the body.
- Males and females look quite similar, although males may have slightly larger fins.
Care Requirements:
- Tank Size: Due to its small size, the Black Yellowtail Blenny can be kept in a minimum tank size of 30 gallons (114 liters). However, larger tanks (50 gallons or more) are ideal to allow for more swimming space and territories.
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Water Parameters:
- Temperature: 72°F to 78°F (22°C to 26°C)
- Salinity: 1.020-1.025 SG
- pH: 8.1-8.4
- Alkalinity: 8-12 dKH
- Ammonia/Nitrites: 0 ppm
- Nitrates: Keep below 20 ppm for optimal health.
- Filtration: A reliable filtration system is necessary, as blennies can be active grazers and produce waste quickly. The water should be clean and well-oxygenated, and the flow should be moderate to strong to replicate their natural environment.
Diet:
- The Black Yellowtail Blenny is primarily herbivorous, feeding on algae and other plant matter in the wild. However, it is an opportunistic feeder and will accept a variety of foods in captivity.
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Diet should include:
- Algae-based foods: Nori (dried seaweed), spirulina, and other algae-based foods.
- Marine vegetables: Blanched spinach, lettuce, and other leafy greens.
- High-quality pellets or flakes: Specifically formulated for herbivorous or omnivorous fish.
- Live rock: Provides a natural grazing source, allowing the blenny to graze on microalgae and detritus.
- You can supplement its diet with occasional meaty foods like frozen mysis shrimp or brine shrimp, but the majority of its diet should consist of plant material.
Behavior and Tankmates:
- Temperament: The Black Yellowtail Blenny is generally peaceful, but it can be somewhat territorial, especially if kept with other blennies or fish that resemble it. It is a curious and active fish that enjoys exploring crevices and rockwork in the aquarium.
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Tankmates:
- It does well with other peaceful fish such as clownfish, gobies, and wrasses.
- It may display some aggression toward other blennies or fish with similar body shapes, so it’s best to avoid keeping multiple blennies in small tanks unless they have plenty of hiding spaces and territories.
- Reef-safe: The Black Yellowtail Blenny is generally reef-safe and does not pose a threat to corals or invertebrates, but it may occasionally nip at certain types of algae.
- It can be kept with reef-safe invertebrates, such as shrimp, crabs, and snails, without any issues.
Special Considerations:
- Hiding Spots: Blennies, including the Black Yellowtail Blenny, love to have rockwork and crevices to hide in. Adding plenty of live rock or structured decor to your tank will provide the fish with a safe place to retreat and explore.
- Jumping: Like many small fish, blennies can be prone to jumping, so it is essential to have a secure lid or cover on the aquarium to prevent them from escaping.
- Acclimation: Blennies can be sensitive when first introduced to a new aquarium, so slow acclimation is recommended to reduce stress.
Reef Compatibility:
- The Black Yellowtail Blenny is generally considered reef-safe, meaning it will not harm corals or invertebrates. It may graze on microalgae, which can help control algae growth in your tank.
- Keep in mind that while the fish is not usually destructive, it may occasionally nip at certain types of delicate coral or algae if it becomes stressed or doesn’t have enough food. Monitoring its behavior when first introduced is a good idea.
Breeding:
- Captive Breeding: Breeding of Black Yellowtail Blennies in captivity is not commonly documented, but like many blennies, they likely engage in territorial mating where males establish territories and court females. However, breeding in a home aquarium is not a frequent occurrence.
Conclusion:
The Black Yellowtail Blenny is a fascinating and colorful species that adds character and beauty to a reef tank. With its peaceful nature and small size, it is ideal for hobbyists with community aquariums, provided there is enough space for it to establish its territory. This active and curious fish is a great algae grazer and will contribute to maintaining a cleaner aquarium. Ensuring a varied diet, appropriate tankmates, and plenty of hiding spots will keep the Black Yellowtail Blenny happy and healthy in your aquarium for years to come