Blennies Care: Tank Setup, Diet, Tank Mates, Diseases & More!

Blennies are fascinating little creatures that are growing in popularity as additions to home aquariums. With their unique behaviors and charming personalities, they offer endless entertainment for those who decide to take on the rewarding task of caring for them.

Blennies care involves providing a suitable aquarium environment, proper diet, and regular maintenance. These small, colorful fish require a well-oxygenated tank with plenty of hiding places and open swimming space. A varied diet of small, meaty foods is necessary for their health and vitality. Some species may also require algae or vegetable matter in their diet.

As a blenny owner myself, I have spent countless hours observing their amusing antics and learning about their specific needs. It is crucial to understand the basics of blenny care, including their ideal tank setup, water conditions, and diet.

Starting with a well-researched plan in place can set the foundation for a thriving and happy blenny. They may be small in size, but these colorful fish will undoubtedly bring big smiles to your face as you watch them dart around your tank, socializing and exploring their underwater world.

Blennies care

Species Summary


Blennies originate from various tropical and subtropical regions of the Atlantic, Pacific, and Indian Oceans. They inhabit diverse marine environments, such as rocky coastlines, coral reefs, and eelgrass beds.


The average lifespan of Blennies is around 3 to 5 years. However, proper husbandry and care can improve their chances of living a longer, healthier life.


Blennies are small, elongated fish with a continuous dorsal fin and scale-less skin. They exhibit a wide range of colors and patterns, depending on the species, making them visually appealing to aquarists.


Blennies typically grow to a length of 4 to 6 inches, although some species may reach up to 8 inches. This small size makes them suitable for various aquarium sizes.

Growth Rate

The growth rate of Blennies varies among species. Generally, they grow faster in their early life stages and slow down as they reach adulthood. Most species reach their mature size within 12 to 18 months.

Behavior & Temperament

Blennies are peaceful and curious creatures, often seen perching on rocks or exploring their surroundings. They enjoy having hiding spots and may become territorial when defending their territory. I once observed my Blenny chasing away a shrimp that was too close to its favorite cave.

Male vs Female

Sexual dimorphism is present in some Blenny species, with males often displaying brighter colors and larger dorsal fins. Moreover, male Blennies are typically more territorial and aggressive during the mating season.

Tank Setup

Tank Size

Blennies are small fish, so it’s essential to provide them with an appropriately sized tank. I’ve found that a minimum of 20 gallons works well for most species, though some larger Blennies may require more space.


For Blennies, moderate lighting is sufficient. I usually use LED lights, which provide enough brightness without producing excessive heat.

Filtration & Aeration

Good filtration and aeration are vital for Blennies’ health. I’d recommend using a powerful, adjustable filter like a hang-on-back or canister filter. Make sure your tank has proper water circulation to maintain oxygen levels.


Blennies are tropical fish, so they need a stable water temperature. I usually set my adjustable heater to maintain temperatures between 72-78°F.


For Blennies, a sandy substrate is ideal, as it allows them to burrow and hide. In my experience, a two-inch layer of fine sand works great.


Provide your Blennies with hiding spots using rocks, caves, or PVC pipes. I once created a custom PVC pipe playground, which my Blennies seemed to love!


Adding live plants not only enhances your tank’s appearance but also offers additional shelter for your Blennies. In my setups, I use both floating and rooted varieties, like Java Fern and Anubias.

Water Quality

Water Temperature

Blennies are tropical fish, so maintaining a stable water temperature is essential. The ideal range is 72-78°F (22-26°C). I remember I had a blenny named Benny, and to keep him comfortable, I invested in a reliable heater and thermometer.

Water pH

Blennies prefer to live in water with a pH level between 8.0-8.3. This can be achieved by regularly testing the water and using natural additives like crushed coral and aragonite sand to help stabilize pH levels.

Water Hardness

Blennies care 3

These little guys thrive in water with a hardness of 8-12 dKH. To maintain this range, I’ve found it helpful to use a quality marine salt mix when preparing new water for changes.

Water Changes

Regular water changes are crucial for keeping your blenny’s environment clean and healthy. It’s essential to perform a 10-20% water change every 1-2 weeks. Here’s a quick guide on how I do it:

  • Test water parameters to ensure stability
  • Prepare new water with marine salt mix
  • Slowly replace the old water with new, temperature-matched water

Tank Maintenance

Keeping a clean and well-maintained tank is essential for the health and happiness of your Blennies.

Water quality is key in maintaining a healthy environment for your fish. Make sure to test the water for ammonia, nitrites, and nitrates regularly, and keep levels stable. In my own experience, I’ve found that weekly water tests help ensure my Blennies thrive.

Conduct weekly water changes of about 10-15% to maintain optimal water quality. Avoid drastic water changes, as it may cause stress to your Blennies.

Remember to clean the substrate at least once a month. Siphoning out detritus prevents it from decomposing and producing toxins.

Be mindful of the filtration system; it needs to be cleaned and maintained regularly. At least once a month, inspect the filter media and replace it if necessary.

Observe the aquarium glass for algae growth. Use an algae scraper or magnet to maintain clarity. When I first started caring for Blennies, I was surprised how quickly algae could accumulate if left unchecked.

Here are some essential tank maintenance tasks:

  • Test water parameters
  • Weekly water changes
  • Clean substrate
  • Inspect and maintain filters
  • Remove algae from aquarium glass

Proper tank maintenance will keep your Blennies healthy, and you’ll have a vibrant and lively aquarium to enjoy!

Tank Mates

Compatible Fish Species

When I was setting up my blenny tank, I realized that blennies are generally peaceful fish and can coexist with a variety of tank mates. Some compatible species include:

  • Clownfish
  • Gobies
  • Cardinalfish

These fish have similar temperaments and space requirements, making them great companions for blennies.

Incompatible Fish Species

However, it’s important to avoid housing blennies with certain species. I once made the mistake of adding a damselfish to my blenny tank, and it caused a lot of stress for the blenny. Some incompatible species are:

  • Damselfish
  • Dottybacks
  • Aggressive angelfish

These fish may harass or even harm your blenny, so it’s best to avoid mixing them together in the same tank.


What To Feed

Blennies are omnivorous fish, which means they require both plant and animal-based foods in their diet. Offer them a variety of high-quality flake foods, pellets, and frozen or live foods. I once had a blenny that absolutely loved munching on live brine shrimp.

Include vegetable matter in their diet by offering them blanched spinach, spirulina flakes, or algae sheets. Some blennies also enjoy grazing on the natural algae growth in the aquarium.


It’s important to feed your blennies 2-3 times a day. Offer them enough food that they can consume in about a minute or two. Regular feeding prevents hunger-induced aggression.

I had a blenny who didn’t get along with some of his tank mates. I noticed that increasing feeding frequency not only helped reduce aggression but also kept them healthier and more energetic.


Here are some helpful tips for feeding your blennies:

  • Keep the water quality optimal for healthy digestion.
  • Be as consistent as possible with feeding times.
  • Monitor your blennies’ eating habits and adjust portion sizes accordingly.
  • Remove uneaten food to prevent water pollution.

Common Diseases


Blennies are generally hardy fish, but they can still suffer from a few common diseases. Some of the most prevalent conditions include ich, velvet, and bacterial infections.


Ich, or white spot disease, is easily recognizable by the tiny white spots that cover the affected fish’s body. Velvet, another parasitic disease, appears as a dusting of gold or rust on the fish’s skin. Bacterial infections usually manifest as reddened or inflamed areas on the fish’s body.


For ich, one effective treatment option is raising the water temperature to 80-82°F and dosing with copper-based medications. For velvet, treating with a copper-based medication in a quarantine tank is recommended. Bacterial infections often require antibiotics such as kanamycin.

I once had a blenny with a bacterial infection, and after treating it with antibiotics, it fully recovered and continued to thrive in my aquarium.


To prevent disease in blennies, follow these practices:

  • Maintain high water quality with regular water changes
  • Use a quarantine tank for new fish or after treating a sick fish
  • Feed a varied and balanced diet
  • Avoid overcrowding

By adhering to these guidelines, you can maintain a healthy and happy environment for your blennies.

Signs of a Healthy Fish

When caring for Blennies, it’s essential to ensure they are in good health. One clear sign is their activity level. A healthy Blenny will be active and display natural behaviors such as foraging and swimming. I once noticed a dramatic change in my Blenny’s activity level, prompting me to quickly check the water conditions.

Another vital sign is their appetite. Blennies are eager feeders, typically feeding on algae and small invertebrates. If they’re eating well, it’s a good indicator of their health.

Proper coloration also plays a significant role. A healthy fish will have vibrant and clear colors without any fading or dullness.

Observing their fins and scales is crucial too. A Blenny with intact fins, free of damage or fraying, and smooth scales is likely healthy.

Keep an eye out for any signs of distress. Healthy Blennies won’t gasp for air or consistently rub themselves against surfaces.

Remember to always monitor your Blennies for these signs to ensure their well-being. It’s essential to quickly address any potential issues to provide the best care for these fascinating creatures.

Signs Your Fish is Sick

Blennies are hardy fish, but as with any pet, they can get sick. Here are a few key signs to look out for when caring for your Blenny.

  1. Loss of appetite: When fish get sick, they often lose interest in food. If your Blenny is refusing to eat, it could be a sign of illness.
  2. Unusual swimming behavior: Blennies have a unique swimming style. Keep an eye out for erratic swimming, as it may indicate a health issue.
  3. Changes in appearance: A healthy Blenny has vibrant colors and clear eyes. If your fish looks dull or has cloudy eyes, it might be a sign of sickness.
  4. Lethargy: Active and curious by nature, Blennies slow down when they’re not feeling well. If your fish is spending more time at the bottom of the tank or hiding, it could be a red flag.
  5. Labored breathing: Just like us, fish breathe harder when they’re sick. If you notice your Blenny breathing more rapidly or struggling, it’s crucial to intervene.

I remember when my Blenny showed signs of illness. It was lethargic and not eating well. I took action immediately and consulted with a marine biologist, who guided me on how to help it recover. The sooner you address your fish’s health, the better the chances of recovery.


Breeding Setup

Blennies care 2

To successfully breed Blennies, I recommend setting up a 20-gallon tank with plenty of hiding spaces. Provide them with rocks, PVC pipes, and artificial plants to create a comfortable environment.

  • Ensure the water temperature is between 75°F to 80°F
  • Maintain a pH between 8.0 to 8.4
  • Keep a specific gravity of 1.020 to 1.025

How To Breed

Sexing Blennies is quite challenging, but males usually have more vibrant colors and longer dorsal fins. To encourage breeding behavior, feed them a varied diet of live or frozen foods.

Some steps to take:

  1. Introduce a pair into the breeding tank
  2. Observe courtship behavior and territorial displays
  3. The male will prepare a nest and entice the female to lay eggs
  4. The female will deposit eggs in the nest, which the male fertilizes


After successful breeding, the male will guard the nest and fan the eggs to keep them oxygenated. Ensure optimal water quality by performing regular water changes. After 7-10 days, the eggs will hatch, and you’ll need to provide the fry with appropriately-sized food like:

  • Rotifers
  • Baby brine shrimp

Keep the fry separate from adults to prevent predation. Regularly monitor their growth and health, gradually introducing them to a regular Blenny diet after several weeks.

Product recommendations for Blennies:

  1. Hikari Marine S Pellets: This fish food is specially formulated for marine fish, including Blennies, and provides a balanced diet for optimal health.
  2. Seachem Stability: This product helps to establish a healthy biological filter in your aquarium, which is important for maintaining good water quality for Blennies.
  3. Fluval Sea Protein Skimmer: This protein skimmer helps to remove organic waste from your aquarium water, which can be harmful to Blennies.
  4. Hydor Koralia Nano Aquarium Circulation Pump: This circulation pump helps to create a natural water flow in your aquarium, which is important for the well-being of Blennies.
  5. Instant Ocean Sea Salt: This sea salt mix is perfect for creating a healthy marine environment for Blennies and other saltwater fish.
  6. API Aquarium Salt: This product helps to promote healthy gill function and reduce stress in fish, including Blennies.
  7. Seachem Prime: This water conditioner helps to detoxify ammonia, nitrite, and nitrate in aquarium water, which can be harmful to Blennies.
  8. Fluval Flex 15 Gallon Aquarium Kit: This aquarium kit is perfect for keeping Blennies in a small space, and comes with a powerful filtration system.
  9. Marina Floating Thermometer: This thermometer helps you to monitor the temperature of your aquarium water, which is important for keeping Blennies healthy.


Caring for Blennies can be a rewarding experience. These small, colorful fish are unique and entertaining. As a beginner, I once faced challenges but eventually found success.

To ensure your Blennies thrive, consider their habitat needs. They require:

  • A tank of at least 20-30 gallons
  • Live rock for hiding and grazing
  • Stable water parameters

Feeding your Blennies is crucial. Provide them with:

  • A variety of foods (algae, frozen, and live)
  • Feeding frequency of 1-2 times per day

Be aware of your Blennies’ temperament. Some species are:

  • Peaceful and suitable for community tanks
  • Semi-aggressive and territorial

In my experience, I found a peaceful Blenny that added personality to the tank. With proper care and attention, your Blennies can flourish, and your marine aquarium will become more diverse and enjoyable. Best of luck on your fishkeeping journey!


Do Blennies need a lot of space?
Blennies are small fish that adapt well to smaller tanks. A 20- to 30-gallon tank is suitable for most species.

What water parameters should I maintain for Blennies?
A stable temperature between 72°F and 78°F, and a pH level between 8.1 and 8.4 are ideal. Keep salinity around 1.024.

What should I feed my Blenny?
Blennies are omnivores. A varied diet of high-quality pellets, live or frozen foods (brine shrimp, mysis shrimp), and fresh veggies (nori) is best.

Can Blennies coexist with other fish in my aquarium?
Most Blennies are peaceful and can coexist with other non-aggressive fish. However, they may defend their territory against similar-looking species.

Do they require hiding spots in the tank?
Yes, Blennies love to explore and hide. Provide them with rocks, caves, and crevices in your aquarium.

I remember when I first got my Blenny, it was shy and didn’t come out of its hiding spot for several days. Give your Blenny time to adjust and create a comfortable environment for it to thrive.

Reference: Wikipedia.


Hi there! My name is Jacob, and I'm the founder of this Pet people blog that talks all about aquarium and fishkeeping. I've been passionate about fish and aquatic life since I was a kid, and I've spent countless hours learning about different species, their habitats, and how to create the perfect environment for them to thrive in.

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