Tailspot Blenny – Species Profile & Care Guide

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You want to craft a unique-looking and stable saltwater community tank, but you have no idea which fish to add and which species are compatible with one another. You are probably already familiarized with the most popular freshwater species like mollies, platies, guppies, swordtails, goldfish, etc.

But if you want to create a reef tank, you might want to know what fish you should get as the first inhabitant. This brings us to a popular choice among reef tank owners, the Tailspot Blenny.

This small and cute fish species is one of the most underrated in the aquarium world due to its predilection towards hiding.

People want more outgoing fish that will dart around the tank and display their coloring and large fins in the light. The Tailspot Blenny is shy and timider than most fish, spending most of its time in the aquarium’s caves and around corals, provided you have any, which you should.

However, the Tailspot Blenny has a unique charm to it which we will assess in today’s article.

Tank Size for Tailspot Blenny

This fish species never grows longer than 2.5 inches. This is the maximum size of a guppy, so the Tailspot Blenny requires similar tank conditions. I suggest providing each fish with 5 gallons of water as a minimum, and I also suggest getting several fish.

The Tailspot Blenny feels more comfortable and safer in a stable group rather than alone. Furthermore, you might want to breed the Blenny, at which point having several of them is a must.

But, breeding and fish comfort aren’t the only aspects to consider when choosing the tank’s size. The Tailspot Blenny requires a specific environment, consisting of caves, corals, and reefs if possible.

They will spend most of their time in hiding, and the coral system is perfect in this sense because it mimics their natural environment.

The rock and coral system is perfect in this sense because it provides optimal conditions for hair algae to grow and feed the Blenny. Hair algae represent this species’ main meal, and the more there are, the healthier and happier your grazing Blenny will be.

I would recommend investing in a 20-gallon tank for a small group of 3-4 Blenny fish and decorating it with a nice cave and coral system. Such a setup will keep your Blenny fish in optimal living conditions, providing them with shelter, food, breeding opportunities, and a calmer state.

Water Requirements for Tailspot Blenny

Fortunately, the Tailspot Blenny isn’t too pretentious about its water conditions. The temperature is one factor that shows little wiggle room. It should remain around 78 to 82 F, as the Blenny prefers warmer and stable water temperature.

Other than that, all water parameters are similar to other tank fish species. The pH should revolve around 7.8 to 8.2, while ammonia and nitrites should remain 0 or close to 0.

With this said, the Blenny requires more stable water parameters in the long run. They don’t do well in unstable environments with fluctuating conditions.

What do Tailspot Blenny Eat?

The Tailspot Blenny is herbivorous, and it’s biologically set to hunt for algae around its environment. You will see your Blenny grazing all day, provided it has enough algae to go around.

This doesn’t mean you should rely on environmental algae for your Blenny’s diet since those won’t suffice. They will most likely need supplementation to remain healthy and full throughout the day, which involves feeding them dry seaweed and algae flakes, preferably coated in multivitamins.

The Blenny needs to eat several times per day, preferably small meals, providing the fish with a steady nutrient intake.

If you keep your Blenny fish in a coral system, the fish might occasionally nip at coral polyps. This is a sign that they’re starving, allowing you to tweak their diets accordingly to prevent this behavior.

How Long do Tailspot Blenny Live?

Tailspot Blenny fish live around 3 to 5 years in captivity in optimal and stable living conditions. The fish will live longer when fed properly and given adequate living conditions with stable water parameters.

The fish’s tank mates also play a crucial role in the quality of their lives.

You shouldn’t keep the Blenny fish with aggressive or overtly inquisitive fish species that may cause the Blenny discomfort.

In essence, the Tailspot Blenny is set to live longer if you meet the following conditions:

  • Change their water regularly (at least once per week) to keep the water clean, healthy, and well-oxygenated
  • Provide a stable and nutritious diet consisting of several smaller meals per day
  • Only pair the Tailspot Blenny with calm and peaceful tank mates
  • Avoid tank mates that share the Blenny’s territory, and that spend their lives near the substrate
  • Keep fewer males than females to avoid male aggression and territorial behavior
  • Quarantine Blenny fish suspect of being sick and provide adequate treatment to promote a fast recovery and protect the rest of the fish population

Do Tailspot Blenny Need a Heater?

Yes, they do. Unlike many fish species, the Tailspot Blenny is a lot more pretentious about its environmental temperature. This species prefers stable water temperatures between 78 to 82 °F, which allows little room for error.

This doesn’t mean that the fish will die if the temperature goes slightly off the charts, but sudden, massive, or repeated fluctuations will hurt the fish.

If the temperature drops or increases too fast, your Blenny may experience temperature shock, which can kill them. The heater will prevent that by keeping the water temperature stable and monitoring environmental temperature day and night.

It also allows you the luxury of adjusting the values depending on the environmental temperature to make sure your Blenny’s environmental conditions remain stable.

Do Tailspot Blenny Need a Filter?

Yes, they do. The problem is that the Blenny is very sensitive to ammonia and nitrites, which is true for most fish species.

The filtering system will do 3 things right:

  • Cleanse the waterA good filter will suck in all water particles, large and small, making the water appear clearer and cleaner. This is a must in a coral-based tank, especially one that houses plants and several fish species. The clearer waters will make for a healthier environment and boost your fish’s natural colors as a result.
  • Control and prevent ammonia and nitrites – The filter counters ammonia and nitrates via 2 essential mechanisms. The first one is via cleaning fish waste and food residues particles floating in the water. This will prevent them from decaying in the tank, increasing ammonia naturally in the process. The second one refers to the filter housing numerous beneficial bacteria that consume ammonia and turn them into nitrites and, consequently, nitrates. The latter compounds are less harmful as fish can assimilate them better in the long run.
  • Oxygenate the environment – The filtering system will also oxygenate your fish’s environment, which benefits all life forms, including plants, bacteria, fish, and other tank inhabitants. Just make sure you don’t set the oxygenating system too high. The Blenny isn’t that fond of strong water currents, which can also disturb the surrounding environment. So, keep it controlled and civil around there.

The filter will also allow you to monitor and control water parameters more effectively. This will allow you to prevent any drastic or sudden changes in water parameters that would affect your Blenny population.

Are Tailspot Blenny Aggressive?

No, they are actually quite docile fish. They will mostly spend their time around the substrate in the cave system that you’ve prepared for them.

They will remain there as much as possible, only going out to eat and swim around for a change.

This doesn’t mean that the Blenny fish are 100% wholesome, always with an olive branch in their mouths. They can also get combative at times, especially towards other fish species invading their territory.

This is why I wouldn’t recommend pairing Blenny fish with any other bottom-dwelling species like loaches or plecos.

Their presence will activate your Blenny’s ugly face, causing them to become aggressive towards the intruders.

The same issue happens between male Blenny fish which are known to become violent against each other. They will compete for territory, females, food, and whatever else any other male fish from any species competes for.

This brings us to an interesting topic – sexual dimorphism. Unfortunately, it’s extremely difficult to sex the Blenny. Males and females are pretty much identical in appearance, and there are no clear-cut markers to refer to when sexing the species.

You can see this confusion on display on numerous fish forums tackling this precise problem.

The only reliable way of solving the issue comes down to getting several fish (5-6) and monitoring the group’s interactions. You should be able to figure out who’s who shortly.

Worst-case scenario, things will become obvious during the mating phase or immediately after, as soon as the female Blenny displays signs of pregnancy.

Unwarranted aggression between 2 fish is also pretty tale-telling, as it suggests that both are males.

As an important note, sexing the Blenny fish accurately is important to prevent aggression and form a stable and flourishing population.

Do Tailspot Blenny Make Good Tank Mates?

Yes, absolutely. The Tailspot Blenny is docile and peaceful and will mind its own business, provided it lives in an optimal setup. This species requires a coral system to thrive, as it provides them with safety, plenty of hiding opportunities, and food.

The Blenny will rarely interact with other fish species, provided they are not overly inquisitive and bother the Blenny too often.

They will only pop out of their hiding when it comes to feeding and assessing their surroundings occasionally.

If they don’t like the company of other fish, they will retreat into hiding immediately. Make sure you don’t pair them with aggressive or large mates that may attack or kill them.

Other than that, so long as your Blenny have a safe area to live in and get adequate food, they will remain healthy and friendly long-term.

How to Breed Tailspot Blenny?

The breeding process is a bit tricky, partly due to Blenny’s almost complete lack of sexual dimorphism. This means it’s unfeasible to rely on a Blenny pair since the likelihood of getting 2 fish of different genders comes down to blind luck.

I recommend getting at least 5-6 Blenny fish to increase your likelihood of getting both males and females in the bunch. The mating process will unfold naturally afterwards, with the female laying the eggs in a cave and allowing the male to fertilize them.

The male will then guard the entrance to the cave, keeping all other fish out, until the eggs hatch. The tiny Tailspot Blenny fish will require stricter care than adults.

This includes having a filter, a heater, and all the necessary equipment to protect the fry and keep the water parameters stable.

Unfortunately, moving the pregnant female into a separate tank isn’t really an option in Blenny’s case. The breeding tank would also have to contain corals and adequate equipment to make sure everything fits the females’ expectations.

But that’s not the only problem. Tailspot Blenny fish are notoriously difficult to accommodate in a different setting as the relocation stresses them out, causing them to grow uncomfortable, aggressive, and even play dead.

And you don’t want that with your pregnant Blenny. So, I would recommend breeding them in the main tank and relying on the fry’s father to protect the offspring.

How to Treat Sick Tailspot Blenny?

Treating this species is the same as treating any other fish. It all comes down to identifying early signs of sickness, quarantining the fish, and applying adequate treatment.

The treatment’s nature, specifics, and duration depend on the disease’s profile. I suggest discussing with a professional should your Blenny fish show any signs of sickness.

Tailspot Blenny fish don’t have any species-specific condition you should worry about. They will mostly face the same health hazards all other tank fish deal with, including mouth fungus, Ich, parasitic infections, etc.

All these can be prevented via a healthy and structured tank maintenance routine, including water changes whenever necessary.


Tailspot Blenny fish make for an interesting addition to any reef tank, decorated with a viable coral system.

They are friendly, peaceful, and will get along with a lot of fish species that share their personality and nothing much else.

Blenny fish can be territorial against fish species invading their habitat, so you might want to keep that in mind when introducing new fish to the tank.

Other than that, provide the Blenny with nutritious meals, allow some algae growth in the tank for extra meals, and keep the water parameters stable, and they will flourish.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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