Blenny Fish Care And Species Profile

blenny fish

Last updated on August 1st, 2022 at 02:38 pm

Blenny fish are small, colorful fish that belong to the Blenniidae family. There are over 200 species of blenny fish, and most of them are marine fish that prefer warmer tropical waters with a little salt. They are unique creatures and fascinating in their own right, which makes them popular additions to aquariums around the world.

A blenny fish refers to several species of marine fish found in Atlantic, Indian and Pacific Ocean waters. They can be identified by their tubular nostrils with an opening above each eye and their large pectoral fins that are nearly as large as their dorsal fin.

Blenny fish can grow to about five inches long in their adulthood, and they prefer living around rocks and coral reefs where they can find plenty of crevices to hide in during the day, coming out at night to feed on smaller fish and crustaceans in the surrounding water.

If you’re considering getting a blenny fish for your aquarium, it’s important to learn more about these creatures first so you can properly care for them and understand their needs.

Origin and descriptions

The blenny fish is an eel-like fish that’s not actually an eel. The name blenny comes from blennius, which is Latin for small scale. Male blennies have developed barbels on their chins, giving them a slight resemblance to catfish. On average, blennies reach around 4 inches in length, but some grow up to 5 inches long!

They live in groups, their colors vary by species, but most blennies are brown or green with white spots. Some species of blenny fish can be found in saltwater, while others prefer freshwater habitats.

Species profile

blenny fish

The blenny fish belongs to the family of fish known as blenniidae. There are approximately 500 species of blennies, and most live in tropical or subtropical waters. The majority of these fish can be found in coral reefs, but some species inhabit tide pools and rocky areas.

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These small fish typically have elongated bodies that taper at both ends. They are usually gray or brown with a mottled pattern. A number of blenny fish are popular aquarium pets because they will eat algae off of glass tanks and rocks.

If you’re interested in keeping one of these fish as a pet, make sure you research your options before purchasing one. Some species may not be suitable for home aquariums due to their territorial nature or aggressive behavior toward other tank mates.

Scientific name

The scientific name of the blenny fish is Blenniiformes


Blennies are typically found on tropical reefs in shallow waters, where they feed primarily on algae. It is also quite common to find blennies in tide pools and mangrove swamps. Although they have been known to live for up to seven years, most survive about two years in captivity. In their natural habitat, it’s not uncommon for them to grow to be 5 inches long. In an aquarium setting, however, it’s not uncommon for them to reach 4 inches or more.

Blenny fish size

Blenny fish are often seen less than 4 inches (10 cm) in length, some species can grow as large as 5 inches (13 cm) or more in length.

Tank size

Due to their small size, the minimum recommended tank size for a blenny fish is 20 gallons (76 liters).

Tank requirements

Live rock is crucial for these fish because it provides them with many hiding places. In addition, blennies also need plenty of swimming room to dart in and out of, so tanks measuring at least 20 gallons will be needed. They do not tolerate low-oxygen conditions well, so you will also need an efficient protein skimmer or quality sponge filter to ensure that oxygen levels remain adequate.

These fish like medium-sized tanks with a rocky substrate, plenty of hiding spots, and low lighting.

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A reef tank is perfect if you’re interested in keeping them, as they can adapt to most aquarium setups. It is important to keep blennies in a tank without any predatory fish, such as clownfish and triggerfish, which might prey on them.

Tank mates

While blennies are generally very hardy, they need to be placed in tanks with compatible tank mates. They should not be housed with fish that will harass them, such as larger aggressive fish or territorial fish that may pick on blennies. Some good tank mates are gobies, small catfish, smaller species of shrimp, and other bottom-dwelling fish.


blenny fish

If you’re looking to keep one of these fish in an aquarium or want to ensure your fish survives and breeds well, it’s important to understand breeding habits. Like most other marine species, blennies will not breed in freshwater. They need brackish water to reproduce successfully.  Brackish water is typically made by mixing fresh and saltwater together—about 1/3 saltwater to 2/3 fresh.

Breeding usually takes place during warmer months when temperatures are between 75-85 degrees Fahrenheit (24-29 degrees Celsius). Males build nests out of algae, rocks, shells, sand or whatever else they can find; females lay eggs inside these nests before males fertilize them with sperm.

The male then guards his nest until fry hatch some days later. It may take up to six weeks for all of the fries to hatch. Male blennies are known to eat their own young if left unguarded. Fry must be removed from their parents as soon as possible so that both parents don’t eat them.

Are they aggressive or peaceful?

Blennies are very peaceful fish. But there’s a bit more to it than that. The vast majority of blennies you’ll find in stores and online are reef-safe and will live harmoniously with other peaceful fish. That said, some species of blenny can be aggressive if kept in insufficient numbers or when not fed properly; however, most species only become territorial when defending eggs or young ones from danger.

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Blenny fish care

blenny fish

These fish are called blennies for a reason. They’re best kept in tanks without other fish or invertebrates that may pick at their delicate skin. Even if you find one without any of these issues, watch out for its sharp fin, which it can use to defend itself from predators (as well as any curious human hands).

Blennies also need clean water with plenty of algae and plants to graze on. In fact, they like having lots of algae to nibble on so much that they often eat more than they should. If you notice your blenny is getting fat around its middle, cut back on feeding time until it’s slimmed down again.

What they eat

Blennies are omnivores, which means they eat both plants and animals. In fact, they sometimes eat other fish! Their teeth—which aren’t very sharp to begin with—are designed to scrape off algae from rocks. They feed on zooplankton, crustaceans, and algae.


blenny fish

The average lifespan of a blenny fish is between 2 and 4 years, with some species living as long as 5 years.

Parasites and diseases

Even if you’re taking proper care of your blenny fish, they may still get sick and need medication to recover. Red-spot disease is caused by overstocking, inadequate filtration and poor diet. Symptoms include tiny red or brownish spots on your blenny’s body. Their defense mechanism isn’t working as well as it should be and they’re suffering from an internal bacterial infection that might be fungal in nature.

Some hobbyists keep their blennies in quarantine for several weeks, to ensure that any parasites or diseases they may have picked up from prior owners are removed from their systems. After your fish is acclimated to its new home and has been quarantined successfully, regularly examine it for signs of infection or disease (which include red streaks on the body, cloudy eyes, not eating normally, and fin/tail rot).

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Predators of adult blenny fish include many larger species of fish, including some species of large-groupers (such as groupers and snappers), pufferfishes, eels, triggerfishes (burrfishes), tuna, barracudas, grouper-like fishes (wrasses), large moray eels, filefish, lionfish, scorpionfish, tilefish, and even dolphins.

Do they make good pets?

If you’re considering adding a blenny fish to your fish tank, then yes, these can make great pets. However, like any other type of pet, there are some things that you need to consider before bringing one home. For example, if you have small children or other pets in your home, it may not be such a good idea to bring home a blenny fish as they have been known to nip at fingers if they feel threatened.

However, most are relatively peaceful and will simply swim around their tank without causing any trouble at all.